refactor: 重构 Agent 模块为 AgentScope，删除旧版 CrewAI/LiteLLM 实现

apps/lib/core/di/injection.dart

@@ -17,6 +17,7 @@ import '../../features/calendar/ui/calendar_state_manager.dart';
 import '../../features/friends/data/friends_api.dart';
 import '../../features/messages/data/inbox_api.dart';
 import '../../features/users/data/users_api.dart';
+import '../../features/todo/data/todo_api.dart';
 
 final sl = GetIt.instance;
 
@@ -65,6 +66,9 @@ Future<void> configureDependencies() async {
   final inboxApi = InboxApi(apiClient);
   sl.registerSingleton<InboxApi>(inboxApi);
 
+  final todoApi = TodoApi(apiClient);
+  sl.registerSingleton<TodoApi>(todoApi);
+
   final authRepository = AuthRepositoryImpl(
     api: authApi,
     tokenStorage: tokenStorage,