refactor(apps): simplify API layer by removing redundant wrapper classes

- Remove ApiClientWrapper and MockApiClientWrapper
- Simplify IApiClient interface
- Update dependency injection configuration
- Optimize calendar service and AG-UI chat models

apps/lib/core/di/injection.dart

@@ -2,6 +2,8 @@ import 'package:dio/dio.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:get_it/get_it.dart';
 import '../api/api_client.dart';
+import '../api/i_api_client.dart';
+import '../api/mock_api_client.dart';
 import '../storage/token_storage.dart';
 import '../config/env.dart';
 import '../../features/auth/data/auth_api.dart';
@@ -13,20 +15,27 @@ import '../../features/calendar/ui/calendar_state_manager.dart';
 final sl = GetIt.instance;
 
 Future<void> configureDependencies() async {
-  if (sl.isRegistered<ApiClient>()) {
+  if (sl.isRegistered<IApiClient>()) {
     await sl.reset();
   }
 
-  final dio = Dio(BaseOptions(baseUrl: Env.apiUrl));
-  final secureStorage = const FlutterSecureStorage();
-  final tokenStorage = SecureTokenStorage(secureStorage);
+  final IApiClient apiClient;
+  final SecureTokenStorage tokenStorage;
 
-  final apiClient = ApiClient(
-    baseUrl: Env.apiUrl,
-    tokenStorage: tokenStorage,
-    dio: dio,
-  );
-  sl.registerSingleton<ApiClient>(apiClient);
+  if (Env.isMockApi) {
+    apiClient = MockApiClient();
+    tokenStorage = SecureTokenStorage(const FlutterSecureStorage());
+  } else {
+    final dio = Dio(BaseOptions(baseUrl: Env.apiUrl));
+    tokenStorage = SecureTokenStorage(const FlutterSecureStorage());
+    apiClient = ApiClient(
+      baseUrl: Env.apiUrl,
+      tokenStorage: tokenStorage,
+      dio: dio,
+    );
+  }
+
+  sl.registerSingleton<IApiClient>(apiClient);
 
   final authApi = AuthApi(apiClient);
   sl.registerSingleton<AuthApi>(authApi);
@@ -37,16 +46,17 @@ Future<void> configureDependencies() async {
   );
   sl.registerSingleton<AuthRepository>(authRepository);
 
-  apiClient.setRefreshCallback((token) async {
-    try {
-      await authRepository.refreshSession(token);
-      return true;
-    } catch (_) {
-      return false;
-    }
-  });
+  if (!Env.isMockApi) {
+    (apiClient as ApiClient).setRefreshCallback((token) async {
+      try {
+        await authRepository.refreshSession(token);
+        return true;
+      } catch (_) {
+        return false;
+      }
+    });
+  }
 
   sl.registerSingleton<AuthBloc>(AuthBloc(authRepository));
-
   sl.registerSingleton<CalendarStateManager>(CalendarStateManager());
 }