feat(mobile): Implement Keycloak WebView authentication with HTTP callback

- Replace flutter_appauth with custom WebView implementation to resolve deep link issues
- Add KeycloakWebViewAuthService with integrated WebView for seamless authentication
- Configure Android manifest for HTTP cleartext traffic support
- Add network security config for development environment (192.168.1.11)
- Update Keycloak client to use HTTP callback endpoint (http://192.168.1.11:8080/auth/callback)
- Remove obsolete keycloak_auth_service.dart and temporary scripts
- Clean up dependencies and regenerate injection configuration
- Tested successfully on multiple Android devices (Xiaomi 2201116TG, SM A725F)

BREAKING CHANGE: Authentication flow now uses WebView instead of external browser
- Users will see Keycloak login page within the app instead of browser redirect
- Resolves ERR_CLEARTEXT_NOT_PERMITTED and deep link state management issues
- Maintains full OIDC compliance with PKCE flow and secure token storage

Technical improvements:
- WebView with custom navigation delegate for callback handling
- Automatic token extraction and user info parsing from JWT
- Proper error handling and user feedback
- Consistent authentication state management across app lifecycle

unionflow-mobile-apps/lib/features/evenements/data/repositories/evenement_repository_impl.dart

@@ -0,0 +1,103 @@
+import 'package:injectable/injectable.dart';
+import '../../../../core/models/evenement_model.dart';
+import '../../../../core/services/api_service.dart';
+import '../../domain/repositories/evenement_repository.dart';
+
+/// Implémentation du repository pour les événements
+/// Utilise l'ApiService pour communiquer avec le backend
+@LazySingleton(as: EvenementRepository)
+class EvenementRepositoryImpl implements EvenementRepository {
+  final ApiService _apiService;
+
+  EvenementRepositoryImpl(this._apiService);
+
+  @override
+  Future<List<EvenementModel>> getEvenementsAVenir({
+    int page = 0,
+    int size = 10,
+  }) async {
+    return await _apiService.getEvenementsAVenir(page: page, size: size);
+  }
+
+  @override
+  Future<List<EvenementModel>> getEvenementsPublics({
+    int page = 0,
+    int size = 20,
+  }) async {
+    return await _apiService.getEvenementsPublics(page: page, size: size);
+  }
+
+  @override
+  Future<List<EvenementModel>> getEvenements({
+    int page = 0,
+    int size = 20,
+    String sortField = 'dateDebut',
+    String sortDirection = 'asc',
+  }) async {
+    return await _apiService.getEvenements(
+      page: page,
+      size: size,
+      sortField: sortField,
+      sortDirection: sortDirection,
+    );
+  }
+
+  @override
+  Future<EvenementModel> getEvenementById(String id) async {
+    return await _apiService.getEvenementById(id);
+  }
+
+  @override
+  Future<List<EvenementModel>> rechercherEvenements(
+    String terme, {
+    int page = 0,
+    int size = 20,
+  }) async {
+    return await _apiService.rechercherEvenements(
+      terme,
+      page: page,
+      size: size,
+    );
+  }
+
+  @override
+  Future<List<EvenementModel>> getEvenementsByType(
+    TypeEvenement type, {
+    int page = 0,
+    int size = 20,
+  }) async {
+    return await _apiService.getEvenementsByType(
+      type,
+      page: page,
+      size: size,
+    );
+  }
+
+  @override
+  Future<EvenementModel> createEvenement(EvenementModel evenement) async {
+    return await _apiService.createEvenement(evenement);
+  }
+
+  @override
+  Future<EvenementModel> updateEvenement(String id, EvenementModel evenement) async {
+    return await _apiService.updateEvenement(id, evenement);
+  }
+
+  @override
+  Future<void> deleteEvenement(String id) async {
+    return await _apiService.deleteEvenement(id);
+  }
+
+  @override
+  Future<EvenementModel> changerStatutEvenement(
+    String id,
+    StatutEvenement nouveauStatut,
+  ) async {
+    return await _apiService.changerStatutEvenement(id, nouveauStatut);
+  }
+
+  @override
+  Future<Map<String, dynamic>> getStatistiquesEvenements() async {
+    return await _apiService.getStatistiquesEvenements();
+  }
+}