极简接口定义和响应定义，支持更多的解析器

apps/im_app/lib/features/login/usecases/login_usecase.dart

@@ -28,9 +28,9 @@ import '../../../domain/repositories/auth_repository.dart';
 ///     → AuthRepository.login()
 ///       → AuthRepositoryImpl.login()
 ///         → _client.executeRequest(LoginRequest)
-///       ← LoginData（DTO）
-///       → _onTokenUpdate(token)               ← 回调写入 Token（内存 + 持久化，由 Provider 层组合）
-///       ← LoginData.toEntity() → User
+///       ← LoginResponse（SDK 已拆包 envelope）
+///       → _onTokenUpdate(accessToken)         ← 回调写入 Token（内存 + 持久化，由 Provider 层组合）
+///       ← LoginResponse.toEntity() → User
 ///     → SocketManager.connect(token)           ← 登录后连接 WebSocket
 ///     → StorageSdkApi.openDatabase(user.id)    ← 按用户 id 打开本地库
 ///   ← User
@@ -41,17 +41,18 @@ class LoginUseCase {
   final ApiConfig _apiConfig;
   final StorageSdkApi _storageApi;
 
-  StorageSdkLifecycle get _storageLifeCycle => _storageApi as StorageSdkLifecycle;
+  StorageSdkLifecycle get _storageLifeCycle =>
+      _storageApi as StorageSdkLifecycle;
 
   LoginUseCase({
     required AuthRepository authRepository,
     required SocketManager socketManager,
     required ApiConfig apiConfig,
     required StorageSdkApi storageApi,
-  })  : _authRepository = authRepository,
-        _socketManager = socketManager,
-        _apiConfig = apiConfig,
-        _storageApi = storageApi;
+  }) : _authRepository = authRepository,
+       _socketManager = socketManager,
+       _apiConfig = apiConfig,
+       _storageApi = storageApi;
 
   /// 执行登录
   ///
@@ -72,10 +73,7 @@ class LoginUseCase {
     _validatePassword(password);
 
     // ── 2. 登录 ──
-    final user = await _authRepository.login(
-      email: email,
-      password: password,
-    );
+    final user = await _authRepository.login(email: email, password: password);
 
     // ── 3. 连接 WebSocket ──
     // token 在 Repository 的 _onTokenUpdate 回调中已写入 ApiConfig，