refactor(apps): 主题系统迁移至 ColorScheme + 扩展架构并支持 Dark Mode

apps/lib/data/repositories/user_repository.dart

@@ -0,0 +1,36 @@
+import '../../core/network/i_api_client.dart';
+import 'models/user_summary.dart';
+
+abstract class UserRepository {
+  Future<UserSummary> getById(String userId);
+  Future<UserSummary> getMe();
+}
+
+class UserRepositoryImpl implements UserRepository {
+  final IApiClient _apiClient;
+  static const _prefix = '/api/v1/users';
+
+  UserRepositoryImpl(this._apiClient);
+
+  @override
+  Future<UserSummary> getById(String userId) async {
+    final response = await _apiClient.get<Map<String, dynamic>>(
+      '$_prefix/$userId',
+    );
+    final user = response.data;
+    if (user == null) {
+      throw StateError('Invalid getById response: empty payload');
+    }
+    return UserSummary.fromJson(user);
+  }
+
+  @override
+  Future<UserSummary> getMe() async {
+    final response = await _apiClient.get<Map<String, dynamic>>('$_prefix/me');
+    final user = response.data;
+    if (user == null) {
+      throw StateError('Invalid getMe response: empty payload');
+    }
+    return UserSummary.fromJson(user);
+  }
+}