Add consent/privacy screen at startup and license display

Implement three privacy features:
1. Consent gate at app startup - users must accept privacy terms before using OciDeck
2. License visibility - MIT license displayed in consent dialog
3. Consent revocation - privacy settings tab allows users to withdraw consent and return to consent screen

Changes:
- New ConsentProvider for managing consent state with SharedPreferences persistence
- New ConsentDialog with privacy explanation and MIT license (expandable)
- Added Privacy tab to settings dialog with revoke consent button
- Updated localization strings for Dutch/English consent screens

Consent flow:
- On first launch or after revocation, consent screen blocks app access
- Users can read privacy terms, view license, and accept to proceed
- Consent can be revoked anytime from Settings → Privacy tab
- After revocation, app returns to consent screen on next launch

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

lib/app.dart

@@ -3,8 +3,10 @@ import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'l10n/app_localizations.dart';
 import 'state/settings_provider.dart';
+import 'state/consent_provider.dart';
 import 'theme/app_theme.dart';
 import 'widgets/app_shell.dart';
+import 'widgets/dialogs/consent_dialog.dart';
 
 class OciDeckApp extends ConsumerWidget {
   const OciDeckApp({super.key});
@@ -47,7 +49,39 @@ class OciDeckApp extends ConsumerWidget {
         GlobalCupertinoLocalizations.delegate,
         GlobalWidgetsLocalizations.delegate,
       ],
-      home: const AppShell(),
+      home: const _ConsentGate(),
     );
   }
 }
+
+class _ConsentGate extends ConsumerWidget {
+  const _ConsentGate();
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final consent = ref.watch(consentProvider);
+
+    if (consent.isLoading) {
+      return Scaffold(
+        body: Center(
+          child: const CircularProgressIndicator(),
+        ),
+      );
+    }
+
+    if (!consent.hasAccepted) {
+      return MaterialApp(
+        title: 'OciDeck',
+        theme: ThemeData.light(),
+        debugShowCheckedModeBanner: false,
+        home: Scaffold(
+          body: Center(
+            child: ConsentDialog(),
+          ),
+        ),
+      );
+    }
+
+    return const AppShell();
+  }
+}

lib/l10n/app_localizations.dart

@@ -4191,5 +4191,22 @@ const _dutchSourceStringAdditions = {
     'Alle afbeeldingen hebben tags.': 'Tur imágen tin tag.',
     'Zet het filter uit om alles weer te zien.':
         'Paga e filter pa mira tur kos atrobe.',
+    'Welkom bij OciDeck': 'Welcome to OciDeck',
+    'Privacy en gebruik': 'Privacy and Usage',
+    'OciDeck is een lokale desktop-applicatie. Uw presentaties en gegevens worden uitsluitend op uw computer opgeslagen.':
+        'OciDeck is a local desktop application. Your presentations and data are stored exclusively on your computer.',
+    'De app verzamelt geen persoonlijke gegevens, geen statistieken en geen gebruiksgegevens. Uw privacy is onze prioriteit.':
+        'The app collects no personal data, no statistics, and no usage data. Your privacy is our priority.',
+    'Alle gegevens die u in OciDeck invoert, blijven op uw lokale systeem en worden niet naar externe servers gestuurd.':
+        'All data you enter in OciDeck remains on your local system and is not sent to external servers.',
+    'Licentie (MIT)': 'License (MIT)',
+    'Door op "Akkoord gaan" te klikken, accepteert u deze voorwaarden en gaat u akkoord met het gebruik van OciDeck.':
+        'By clicking "Agree", you accept these terms and agree to the use of OciDeck.',
+    'Volledige licentie online': 'Full license online',
+    'Akkoord gaan': 'Agree',
+    'Toestemming intrekken': 'Revoke Consent',
+    'Toestemming ingetrokken': 'Consent revoked',
+    'U moet eerst de privacy- en gebruiksvoorwaarden accepteren voordat u OciDeck kunt gebruiken.':
+        'You must accept the privacy and usage terms before you can use OciDeck.',
   },
 };

lib/state/consent_provider.dart

@@ -0,0 +1,67 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+const _consentKey = 'app_consent_accepted';
+
+final consentProvider =
+    NotifierProvider<ConsentNotifier, ConsentState>(() {
+  return ConsentNotifier();
+});
+
+class ConsentState {
+  final bool hasAccepted;
+  final bool isLoading;
+
+  const ConsentState({
+    required this.hasAccepted,
+    this.isLoading = false,
+  });
+
+  ConsentState copyWith({
+    bool? hasAccepted,
+    bool? isLoading,
+  }) {
+    return ConsentState(
+      hasAccepted: hasAccepted ?? this.hasAccepted,
+      isLoading: isLoading ?? this.isLoading,
+    );
+  }
+}
+
+class ConsentNotifier extends Notifier<ConsentState> {
+  @override
+  ConsentState build() {
+    _initialize();
+    return const ConsentState(hasAccepted: false, isLoading: true);
+  }
+
+  Future<void> _initialize() async {
+    try {
+      final prefs = await SharedPreferences.getInstance();
+      final hasAccepted = prefs.getBool(_consentKey) ?? false;
+      state = state.copyWith(hasAccepted: hasAccepted, isLoading: false);
+    } catch (e) {
+      state = state.copyWith(isLoading: false);
+    }
+  }
+
+  Future<void> acceptConsent() async {
+    try {
+      final prefs = await SharedPreferences.getInstance();
+      await prefs.setBool(_consentKey, true);
+      state = state.copyWith(hasAccepted: true);
+    } catch (e) {
+      state = state.copyWith(hasAccepted: true);
+    }
+  }
+
+  Future<void> revokeConsent() async {
+    try {
+      final prefs = await SharedPreferences.getInstance();
+      await prefs.setBool(_consentKey, false);
+      state = state.copyWith(hasAccepted: false);
+    } catch (e) {
+      state = state.copyWith(hasAccepted: false);
+    }
+  }
+}

lib/widgets/dialogs/consent_dialog.dart

@@ -0,0 +1,188 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:url_launcher/url_launcher.dart';
+import '../../l10n/app_localizations.dart';
+import '../../state/consent_provider.dart';
+
+class ConsentDialog extends ConsumerStatefulWidget {
+  const ConsentDialog({super.key});
+
+  @override
+  ConsumerState<ConsentDialog> createState() => _ConsentDialogState();
+}
+
+class _ConsentDialogState extends ConsumerState<ConsentDialog> {
+  bool _licenseExpanded = false;
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+    final theme = Theme.of(context);
+
+    return AlertDialog(
+      title: Text(l10n.d('Welkom bij OciDeck')),
+      content: SizedBox(
+        width: 600,
+        child: SingleChildScrollView(
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              // Privacy & Use Explanation
+              Text(
+                l10n.d('Privacy en gebruik'),
+                style: const TextStyle(
+                  fontSize: 14,
+                  fontWeight: FontWeight.w600,
+                ),
+              ),
+              const SizedBox(height: 10),
+              Container(
+                padding: const EdgeInsets.all(12),
+                decoration: BoxDecoration(
+                  color: theme.colorScheme.surface,
+                  border: Border.all(
+                    color: theme.colorScheme.outlineVariant,
+                  ),
+                  borderRadius: BorderRadius.circular(8),
+                ),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      l10n.d(
+                        'OciDeck is een lokale desktop-applicatie. Uw presentaties en gegevens worden uitsluitend op uw computer opgeslagen.',
+                      ),
+                      style: const TextStyle(fontSize: 12),
+                    ),
+                    const SizedBox(height: 10),
+                    Text(
+                      l10n.d(
+                        'De app verzamelt geen persoonlijke gegevens, geen statistieken en geen gebruiksgegevens. Uw privacy is onze prioriteit.',
+                      ),
+                      style: const TextStyle(fontSize: 12),
+                    ),
+                    const SizedBox(height: 10),
+                    Text(
+                      l10n.d(
+                        'Alle gegevens die u in OciDeck invoert, blijven op uw lokale systeem en worden niet naar externe servers gestuurd.',
+                      ),
+                      style: const TextStyle(fontSize: 12),
+                    ),
+                  ],
+                ),
+              ),
+              const SizedBox(height: 18),
+              // License Section
+              ExpansionTile(
+                title: Text(
+                  l10n.d('Licentie (MIT)'),
+                  style: const TextStyle(
+                    fontSize: 14,
+                    fontWeight: FontWeight.w600,
+                  ),
+                ),
+                initiallyExpanded: _licenseExpanded,
+                onExpansionChanged: (expanded) {
+                  setState(() => _licenseExpanded = expanded);
+                },
+                children: [
+                  Container(
+                    padding: const EdgeInsets.all(12),
+                    decoration: BoxDecoration(
+                      color: theme.colorScheme.surface,
+                      border: Border.all(
+                        color: theme.colorScheme.outlineVariant,
+                      ),
+                      borderRadius: BorderRadius.circular(8),
+                    ),
+                    constraints: const BoxConstraints(maxHeight: 250),
+                    child: SingleChildScrollView(
+                      child: Text(
+                        l10n.d(_getLicenseText()),
+                        style: const TextStyle(
+                          fontSize: 11,
+                          fontFamily: 'monospace',
+                          color: Color(0xFF475569),
+                        ),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+              const SizedBox(height: 18),
+              // Confirmation Section
+              Container(
+                padding: const EdgeInsets.all(12),
+                decoration: BoxDecoration(
+                  color: theme.colorScheme.primaryContainer
+                      .withValues(alpha: 0.2),
+                  border: Border.all(
+                    color: theme.colorScheme.primary.withValues(alpha: 0.3),
+                  ),
+                  borderRadius: BorderRadius.circular(8),
+                ),
+                child: Text(
+                  l10n.d(
+                    'Door op "Akkoord gaan" te klikken, accepteert u deze voorwaarden en gaat u akkoord met het gebruik van OciDeck.',
+                  ),
+                  style: const TextStyle(
+                    fontSize: 12,
+                    fontWeight: FontWeight.w500,
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => _launchLicense(context),
+          child: Text(l10n.d('Volledige licentie online')),
+        ),
+        const Spacer(),
+        ElevatedButton(
+          onPressed: () => _acceptConsent(ref),
+          child: Text(l10n.d('Akkoord gaan')),
+        ),
+      ],
+    );
+  }
+
+  String _getLicenseText() {
+    return '''MIT License
+
+Copyright (c) 2024 De Winter Information Solutions
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.''';
+  }
+
+  void _launchLicense(BuildContext context) async {
+    const url =
+        'https://github.com/yourusername/ocideck/blob/main/LICENSE.md';
+    if (await canLaunchUrl(Uri.parse(url))) {
+      await launchUrl(Uri.parse(url), mode: LaunchMode.externalApplication);
+    }
+  }
+
+  void _acceptConsent(WidgetRef ref) {
+    ref.read(consentProvider.notifier).acceptConsent();
+  }
+}

lib/widgets/dialogs/settings_dialog.dart

@@ -5,6 +5,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../models/settings.dart';
 import '../../state/settings_provider.dart';
 import '../../state/tabs_provider.dart';
+import '../../state/consent_provider.dart';
 import '../../theme/app_theme.dart';
 import '../../l10n/app_localizations.dart';
 
@@ -191,7 +192,7 @@ class _SettingsDialogState extends ConsumerState<SettingsDialog> {
         : profiles.first.name;
 
     return DefaultTabController(
-      length: 5,
+      length: 6,
       child: AlertDialog(
         title: Text(l10n.t('settings')),
         content: SizedBox(
@@ -223,6 +224,10 @@ class _SettingsDialogState extends ConsumerState<SettingsDialog> {
                     icon: const Icon(Icons.image_outlined),
                     text: l10n.t('settingsLogo'),
                   ),
+                  Tab(
+                    icon: const Icon(Icons.privacy_tip_outlined),
+                    text: l10n.d('Privacy'),
+                  ),
                 ],
               ),
               const SizedBox(height: 12),
@@ -234,6 +239,7 @@ class _SettingsDialogState extends ConsumerState<SettingsDialog> {
                     _tabBody(_styleTab(profiles, dropdownValue)),
                     _tabBody(_colorsTab()),
                     _tabBody(_logoTab()),
+                    _tabBody(_privacyTab()),
                   ],
                 ),
               ),
@@ -1623,4 +1629,83 @@ class _SettingsDialogState extends ConsumerState<SettingsDialog> {
     );
     return Color(value ?? 0xFFFFFFFF);
   }
+
+  Widget _privacyTab() {
+    final l10n = context.l10n;
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        _sectionTitle(l10n.d('Toestemming')),
+        Container(
+          padding: const EdgeInsets.all(12),
+          decoration: BoxDecoration(
+            color: const Color(0xFFF0F9FF),
+            border: Border.all(color: const Color(0xFFBFDBFE)),
+            borderRadius: BorderRadius.circular(8),
+          ),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Text(
+                l10n.d('U hebt al toegestemd in het gebruik van OciDeck.'),
+                style: const TextStyle(fontSize: 12, fontWeight: FontWeight.w500),
+              ),
+              const SizedBox(height: 8),
+              Text(
+                l10n.d(
+                  'U kunt uw toestemming op elk moment intrekken. Na intrekking moet u deze voorwaarden opnieuw accepteren.',
+                ),
+                style: const TextStyle(fontSize: 11, color: Color(0xFF475569)),
+              ),
+            ],
+          ),
+        ),
+        const SizedBox(height: 16),
+        Center(
+          child: ElevatedButton.icon(
+            onPressed: _revokeConsent,
+            icon: const Icon(Icons.undo, size: 16),
+            label: Text(l10n.d('Toestemming intrekken')),
+            style: ElevatedButton.styleFrom(
+              backgroundColor: Colors.red[600],
+              foregroundColor: Colors.white,
+            ),
+          ),
+        ),
+      ],
+    );
+  }
+
+  void _revokeConsent() {
+    final l10n = context.l10n;
+    showDialog<void>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: Text(l10n.d('Toestemming intrekken?')),
+        content: Text(
+          l10n.d(
+            'Als u uw toestemming intrekt, moet u deze voorwaarden opnieuw accepteren wanneer u OciDeck opnieuw start.',
+          ),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(ctx),
+            child: Text(l10n.t('cancel')),
+          ),
+          ElevatedButton(
+            onPressed: () {
+              ref.read(consentProvider.notifier).revokeConsent();
+              Navigator.pop(ctx);
+              Navigator.pop(context);
+            },
+            style: ElevatedButton.styleFrom(backgroundColor: Colors.red[600]),
+            child: Text(
+              l10n.d('Intrekken'),
+              style: const TextStyle(color: Colors.white),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
 }