完整实现 Swarm 多智能体协作系统

- 新增 CLIPluginAdapter 统一接口 (backend/app/core/agent_adapter.py)
- 新增 LLM 服务层，支持 Anthropic/OpenAI/DeepSeek/Ollama (backend/app/services/llm_service.py)
- 新增 Agent 执行引擎，支持文件锁自动管理 (backend/app/services/agent_executor.py)
- 新增 NativeLLMAgent 原生 LLM 适配器 (backend/app/adapters/native_llm_agent.py)
- 新增进程管理器 (backend/app/services/process_manager.py)
- 新增 Agent 控制 API (backend/app/routers/agents_control.py)
- 新增 WebSocket 实时通信 (backend/app/routers/websocket.py)
- 更新前端 AgentsPage，支持启动/停止 Agent
- 测试通过：Agent 启动、批量操作、栅栏同步

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/utils/singleton.py

@@ -0,0 +1,58 @@
+"""
+单例模式工具模块 - 统一管理全局服务实例
+"""
+
+from typing import TypeVar, Type, Dict, Callable, Optional
+
+T = TypeVar('T')
+
+
+class SingletonRegistry:
+    """单例注册表 - 统一管理所有服务实例"""
+
+    _instances: Dict[str, object] = {}
+    _factories: Dict[str, Callable[[], object]] = {}
+
+    @classmethod
+    def register(cls, name: str, factory: Callable[[], T]) -> None:
+        """注册服务工厂函数"""
+        cls._factories[name] = factory
+
+    @classmethod
+    def get(cls, name: str, instance_type: Type[T]) -> T:
+        """获取或创建服务实例"""
+        if name not in cls._instances:
+            if name not in cls._factories:
+                raise KeyError(f"未注册的服务: {name}")
+            cls._instances[name] = cls._factories[name]()
+        return cls._instances[name]
+
+    @classmethod
+    def reset(cls, name: Optional[str] = None) -> None:
+        """重置服务实例（用于测试）"""
+        if name:
+            cls._instances.pop(name, None)
+        else:
+            cls._instances.clear()
+
+
+def singleton_factory(factory: Callable[[], T]) -> Callable[[], T]:
+    """
+    单例工厂装饰器
+
+    用法:
+        @singleton_factory
+        def get_service():
+            return Service()
+
+        service = get_service()  # 始终返回同一实例
+    """
+    instance: Optional[T] = None
+
+    def wrapper() -> T:
+        nonlocal instance
+        if instance is None:
+            instance = factory()
+        return instance
+
+    return wrapper