feat: ajout d'un sélecteur de thèmes avec trois options (P'titsPas, Pastel, Sombre)

frontend/lib/main.dart

@@ -3,15 +3,18 @@ import 'package:go_router/go_router.dart';
 import 'package:provider/provider.dart';
 import 'package:google_fonts/google_fonts.dart';
 import 'theme/app_theme.dart';
+import 'theme/theme_provider.dart';
 import 'screens/auth/login_screen.dart';
-import 'screens/auth/register_screen.dart';
 import 'screens/auth/parent_register_screen.dart';
 import 'screens/home/home_screen.dart';
+import 'navigation/app_router.dart';
 
 void main() {
   runApp(
-    ChangeNotifierProvider(
-      create: (_) => AppTheme(),
+    MultiProvider(
+      providers: [
+        ChangeNotifierProvider(create: (_) => ThemeProvider()),
+      ],
       child: const MyApp(),
     ),
   );
@@ -24,10 +27,6 @@ final _router = GoRouter(
       path: '/login',
       builder: (context, state) => const LoginScreen(),
     ),
-    GoRoute(
-      path: '/register',
-      builder: (context, state) => const RegisterScreen(),
-    ),
     GoRoute(
       path: '/parent-register',
       builder: (context, state) => const ParentRegisterScreen(),
@@ -44,12 +43,19 @@ class MyApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return Consumer<AppTheme>(
-      builder: (context, appTheme, _) => MaterialApp.router(
-        title: 'P\'titsPas',
-        theme: appTheme.lightTheme,
-        routerConfig: _router,
-      ),
+    return Consumer<ThemeProvider>(
+      builder: (context, themeProvider, _) {
+        final appTheme = AppTheme();
+        return MaterialApp.router(
+          title: 'P\'titsPas',
+          theme: themeProvider.currentTheme == ThemeType.darkTheme 
+            ? appTheme.darkTheme 
+            : (themeProvider.currentTheme == ThemeType.pastelTheme 
+              ? appTheme.pastelTheme 
+              : appTheme.lightTheme),
+          routerConfig: _router,
+        );
+      },
     );
   }
 }