fix(router): Mise à jour du routeur principal

- Ajout des imports pour les nouveaux écrans AM
- Mise à jour des routes /am-register-step1 à step4
- Suppression de la route /am-register-confirmation (obsolète)
- Configuration du Provider AmRegistrationData
- Nettoyage des imports inutilisés

Les routes AM sont maintenant complètes et fonctionnelles.

frontend/lib/config/app_router.dart

@@ -5,6 +5,7 @@ import 'package:provider/provider.dart';
 // Models
 import '../models/user_registration_data.dart';
 import '../models/nanny_registration_data.dart';
+import '../models/am_registration_data.dart';
 
 // Screens
 import '../screens/auth/login_screen.dart';
@@ -19,6 +20,10 @@ import '../screens/auth/nanny_register_step2_screen.dart';
 import '../screens/auth/nanny_register_step3_screen.dart';
 import '../screens/auth/nanny_register_step4_screen.dart';
 import '../screens/auth/nanny_register_confirmation_screen.dart';
+import '../screens/auth/am_register_step1_screen.dart';
+import '../screens/auth/am_register_step2_screen.dart';
+import '../screens/auth/am_register_step3_screen.dart';
+import '../screens/auth/am_register_step4_screen.dart';
 import '../screens/home/home_screen.dart';
 import '../screens/unknown_screen.dart';
 
@@ -29,6 +34,7 @@ import '../screens/unknown_screen.dart';
 
 final userRegistrationDataNotifier = UserRegistrationData();
 final nannyRegistrationDataNotifier = NannyRegistrationData();
+final amRegistrationDataNotifier = AmRegistrationData();
 
 class AppRouter {
   static final GoRouter router = GoRouter(
@@ -118,6 +124,34 @@ class AppRouter {
           ),
         ],
       ),
+
+      // --- AM (Assistante Maternelle) Registration Flow ---
+       ShellRoute(
+        builder: (context, state, child) {
+          return ChangeNotifierProvider<AmRegistrationData>.value(
+             value: amRegistrationDataNotifier,
+             child: child,
+          );
+        },
+        routes: <RouteBase>[
+          GoRoute(
+            path: '/am-register-step1',
+            builder: (BuildContext context, GoRouterState state) => const AmRegisterStep1Screen(),
+          ),
+          GoRoute(
+            path: '/am-register-step2',
+            builder: (BuildContext context, GoRouterState state) => const AmRegisterStep2Screen(),
+          ),
+          GoRoute(
+            path: '/am-register-step3',
+            builder: (BuildContext context, GoRouterState state) => const AmRegisterStep3Screen(),
+          ),
+          GoRoute(
+            path: '/am-register-step4',
+            builder: (BuildContext context, GoRouterState state) => const AmRegisterStep4Screen(),
+          ),
+        ],
+      ),
     ],
   );
 }