refactor: 移除前端 Mock API，新增共享组件，优化认证流程

- 删除 mock_api_client、mock_calendar_service、mock_history_service
- 新增 fixed_length_code_input、link_button、message_composer 共享组件
- 优化登录/注册/密码重置页面使用新组件
- 简化 injection.dart 移除 mock 分支
- 更新 env.dart 配置（BACKEND_URL 替换 API_URL）
- 后端 agentscope 工具和测试更新
- 重构 AGENTS.md 文档结构
- 新增 deploy/ 目录和 protocol 文档

apps/lib/features/chat/presentation/bloc/chat_bloc.dart

@@ -4,7 +4,6 @@ import 'dart:typed_data';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:social_app/core/api/i_api_client.dart';
-import 'package:social_app/core/api/mock_api_client.dart';
 import 'package:social_app/core/di/injection.dart';
 
 import '../../data/models/ag_ui_event.dart';
@@ -91,16 +90,8 @@ class ChatBloc extends Cubit<ChatState> {
   final Map<String, Future<Uint8List?>> _attachmentPreviewInflight =
       <String, Future<Uint8List?>>{};
 
-  ChatBloc({AgUiService? service, IApiClient? apiClient})
-    : _service =
-          service ??
-          AgUiService(
-            apiClient:
-                apiClient ??
-                (sl.isRegistered<IApiClient>()
-                    ? sl<IApiClient>()
-                    : MockApiClient()),
-          ),
+  ChatBloc({AgUiService? service, required IApiClient apiClient})
+    : _service = service ?? AgUiService(apiClient: apiClient),
       super(const ChatState()) {
     _service.onEvent = _handleEvent;
   }