feat: localisation with en, de, fr and it

lib/main.dart

@@ -15,6 +15,8 @@ import 'core/auth/auth_state_manager.dart';
 import 'core/utils/debug_logger.dart';
 
 import 'features/onboarding/views/onboarding_sheet.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:conduit/l10n/app_localizations.dart';
 import 'features/chat/views/chat_page.dart';
 import 'features/navigation/views/splash_launcher_page.dart';
 
@@ -85,17 +87,40 @@ class _ConduitAppState extends ConsumerState<ConduitApp> {
         ? AppTheme.conduitDarkTheme
         : AppTheme.conduitLightTheme;
 
+    final locale = ref.watch(localeProvider);
+
     return AnimatedThemeWrapper(
       theme: currentTheme,
       duration: AnimationDuration.medium,
       child: ErrorBoundary(
         child: MaterialApp(
-          title: 'Conduit',
+          onGenerateTitle: (context) => AppLocalizations.of(context)!.appTitle,
           theme: AppTheme.conduitLightTheme,
           darkTheme: AppTheme.conduitDarkTheme,
           themeMode: themeMode,
           debugShowCheckedModeBanner: false,
           navigatorKey: NavigationService.navigatorKey,
+          locale: locale,
+          localizationsDelegates: const [
+            AppLocalizations.delegate,
+            GlobalMaterialLocalizations.delegate,
+            GlobalWidgetsLocalizations.delegate,
+            GlobalCupertinoLocalizations.delegate,
+          ],
+          supportedLocales: const [
+            Locale('en'),
+            Locale('de'),
+            Locale('fr'),
+            Locale('it'),
+          ],
+          localeResolutionCallback: (deviceLocale, supported) {
+            if (locale != null) return locale; // User override wins
+            if (deviceLocale == null) return const Locale('en');
+            for (final loc in supported) {
+              if (loc.languageCode == deviceLocale.languageCode) return loc;
+            }
+            return const Locale('en');
+          },
           builder: (context, child) {
             // Keep a subtle fade for navigation transitions only
             final wrapped = OfflineIndicator(
@@ -159,7 +184,7 @@ class _ConduitAppState extends ConsumerState<ConduitApp> {
 
             if (authNavState == AuthNavigationState.error) {
               return _buildErrorState(
-                ref.watch(authErrorProvider3) ?? 'Authentication error',
+                ref.watch(authErrorProvider3) ?? AppLocalizations.of(context)!.errorMessage,
               );
             }
 
@@ -174,7 +199,7 @@ class _ConduitAppState extends ConsumerState<ConduitApp> {
           loading: () => _buildInitialLoadingSkeleton(context),
           error: (error, stackTrace) {
             DebugLogger.error('Server provider error', error);
-            return _buildErrorState('Server connection failed: $error');
+            return _buildErrorState(AppLocalizations.of(context)!.unableToConnectServer);
           },
         );
       },
@@ -268,7 +293,7 @@ class _ConduitAppState extends ConsumerState<ConduitApp> {
               ),
               const SizedBox(height: Spacing.md),
               Text(
-                'Initialization Failed',
+                AppLocalizations.of(context)!.initializationFailed,
                 style: TextStyle(
                   fontSize: AppTypography.headlineLarge,
                   fontWeight: FontWeight.bold,
@@ -291,7 +316,7 @@ class _ConduitAppState extends ConsumerState<ConduitApp> {
                   backgroundColor: context.conduitTheme.buttonPrimary,
                   foregroundColor: context.conduitTheme.buttonPrimaryText,
                 ),
-                child: const Text('Retry'),
+                child: Text(AppLocalizations.of(context)!.retry),
               ),
             ],
           ),