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/core/models/membre_model.dart

@@ -115,6 +115,32 @@ class MembreModel extends Equatable {
     return parts.join(', ');
   }
 
+  /// Libellé du statut formaté
+  String get statutLibelle {
+    switch (statut.toUpperCase()) {
+      case 'ACTIF':
+        return 'Actif';
+      case 'INACTIF':
+        return 'Inactif';
+      case 'SUSPENDU':
+        return 'Suspendu';
+      default:
+        return statut;
+    }
+  }
+
+  /// Âge calculé à partir de la date de naissance
+  int get age {
+    if (dateNaissance == null) return 0;
+    final now = DateTime.now();
+    int age = now.year - dateNaissance!.year;
+    if (now.month < dateNaissance!.month ||
+        (now.month == dateNaissance!.month && now.day < dateNaissance!.day)) {
+      age--;
+    }
+    return age;
+  }
+
   /// Copie avec modifications
   MembreModel copyWith({
     String? id,