Add WebSocket support and enhance chat functionality

- Implement WebSocket handling in the FastCGI server, allowing for real-time communication.
- Introduce functions for managing WebSocket connections, broadcasting messages, and sending to specific connections.
- Create a chat interface in the `websockets.ws.uce` file, including message handling and user notifications.
- Refactor existing code to accommodate WebSocket integration, ensuring compatibility with HTTP requests.
- Update documentation to reflect new features and usage instructions for WebSocket functionality.

src/lib/compiler.h

@@ -1,4 +1,5 @@
 #define RENDER() extern "C" void render(DTree& call)
+#define WS() extern "C" void websocket(DTree& call)
 #define EXPORT extern "C"
 
 String process_html_literal(Request* context, SharedUnit* su, String content);
@@ -8,6 +9,7 @@ void load_shared_unit(Request* context, SharedUnit* su, String file_name);
 void compile_shared_unit(Request* context, SharedUnit* su, String file_name);
 SharedUnit* get_shared_unit(Request* context, String file_name, bool opt_so_optional = false);
 void compiler_invoke(Request* context, String file_name, DTree& call_param);
+void compiler_invoke_websocket(Request* context, String file_name, DTree& call_param);
 SharedUnit* compiler_load_shared_unit(Request* context, String file_name, String current_path = "", bool opt_so_optional = false);
 
 SharedUnit* load_file(String file_name);