feat: 优化WebSocket连接和心跳机制

- 在main.py和standalone.py中添加ws_ping_interval和ws_ping_timeout配置
- 调整ws.py中的心跳发送逻辑，先发送ping再等待
- 在host_client中优化消息处理，使用任务队列处理转发请求
- 更新WebTool以适配新的API格式并增加搜索结果限制
- 在agent.py中添加日期显示和web调用次数限制
- 修复bot/handler.py中的事件循环问题

bot/handler.py

@@ -184,6 +184,14 @@ def start_websocket_client(loop: asyncio.AbstractEventLoop) -> None:
         backoff = 1.0
         max_backoff = 60.0
 
+        # lark_oapi.ws.client captures the event loop at module import time.
+        # In standalone mode uvicorn already owns the main loop, so we create
+        # a fresh loop for this thread and redirect the lark module to use it.
+        thread_loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(thread_loop)
+        import lark_oapi.ws.client as _lark_ws_client
+        _lark_ws_client.loop = thread_loop
+
         while True:
             try:
                 _ws_connected = False