feat: Intégration du frontend Flutter depuis YNOV

- Framework: Flutter web
- Pages: Login, inscription, dashboards
- Services: API client, authentification, gestion d'état
- Intégration avec backend NestJS
- Dockerfile pour déploiement web

frontend/lib/services/api/api_config.dart

@@ -0,0 +1,32 @@
+class ApiConfig {
+  // static const String baseUrl = 'http://localhost:3000/api/v1/';
+  static const String baseUrl = 'https://ynov.ptits-pas.fr/api/v1';
+
+  // Auth endpoints
+  static const String login = '/auth/login';
+  static const String register = '/auth/register';
+  static const String refreshToken = '/auth/refresh';
+
+  // Users endpoints
+  static const String users = '/users';
+  static const String userProfile = '/users/profile';
+  static const String userChildren = '/users/children';
+
+  // Dashboard endpoints
+  static const String dashboard = '/dashboard';
+  static const String events = '/events';
+  static const String contracts = '/contracts';
+  static const String conversations = '/conversations';
+  static const String notifications = '/notifications';
+
+   // Headers
+  static Map<String, String> get headers => {
+    'Content-Type': 'application/json',
+    'Accept': 'application/json',
+  };
+
+  static Map<String, String> authHeaders(String token) => {
+    ...headers,
+    'Authorization': 'Bearer $token',
+  };
+}