feat: 集成MCP统一外部接口管理系统

- 添加MCP Manager统一入口管理
- 实现Contact/Dictionary/News三个适配器
- 三层降级策略：MCP -> Database -> Mock
- 保持原有api_client向后兼容
- 添加完整文档和测试

backend/app/mcp/mcp_manager.py

@@ -0,0 +1,114 @@
+"""
+MCP管理器
+统一管理所有MCP适配器和外部接口
+"""
+from typing import Dict, Any, Optional, List, Type
+from .mcp_client import MCPClient, MCPServerConfig
+from .adapters.base_adapter import BaseAdapter, AdapterResult
+
+
+class MCPManager:
+    """
+    MCP管理器
+    
+    职责：
+    1. 管理MCP客户端
+    2. 注册和管理适配器
+    3. 提供统一的调用接口
+    """
+    
+    def __init__(self):
+        self._mcp_client = MCPClient()
+        self._adapters: Dict[str, BaseAdapter] = {}
+        self._initialized = False
+    
+    def configure_servers(self, servers_config: Dict[str, Dict[str, Any]]):
+        """
+        配置MCP服务器
+        
+        Args:
+            servers_config: 服务器配置字典
+                {
+                    "filesystem": {
+                        "command": "npx",
+                        "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path"]
+                    },
+                    "news": {...}
+                }
+        """
+        for name, config in servers_config.items():
+            server_config = MCPServerConfig(
+                name=name,
+                server_type=config.get("type", "stdio"),
+                command=config.get("command"),
+                args=config.get("args", []),
+                url=config.get("url"),
+                headers=config.get("headers", {}),
+                env=config.get("env", {}),
+                enabled=config.get("enabled", True)
+            )
+            self._mcp_client.register_server(server_config)
+    
+    def register_adapter(self, adapter: BaseAdapter):
+        """注册适配器"""
+        adapter.mcp_client = self._mcp_client
+        self._adapters[adapter.name] = adapter
+    
+    def get_adapter(self, name: str) -> Optional[BaseAdapter]:
+        """获取适配器"""
+        return self._adapters.get(name)
+    
+    async def initialize(self):
+        """初始化MCP系统"""
+        if self._initialized:
+            return
+        
+        await self._mcp_client.initialize()
+        
+        # 初始化所有适配器
+        for name, adapter in self._adapters.items():
+            print(f"[MCP] 初始化适配器: {name}")
+        
+        self._initialized = True
+        print(f"[MCP] 管理器初始化完成，适配器: {list(self._adapters.keys())}")
+    
+    async def execute(
+        self,
+        adapter_name: str,
+        action: str,
+        **kwargs
+    ) -> AdapterResult:
+        """
+        统一执行接口
+        
+        Args:
+            adapter_name: 适配器名称
+            action: 操作类型
+            **kwargs: 操作参数
+            
+        Returns:
+            AdapterResult: 执行结果
+        """
+        if not self._initialized:
+            await self.initialize()
+        
+        adapter = self._adapters.get(adapter_name)
+        if not adapter:
+            return AdapterResult(
+                success=False,
+                error=f"适配器 {adapter_name} 不存在"
+            )
+        
+        return await adapter.execute(action, **kwargs)
+    
+    def get_available_adapters(self) -> List[str]:
+        """获取所有可用适配器"""
+        return list(self._adapters.keys())
+    
+    def get_available_tools(self) -> List[str]:
+        """获取所有可用MCP工具"""
+        return self._mcp_client.get_available_tools()
+
+
+# 全局单例
+mcp_manager = MCPManager()