fix: 修复聊天系统编译错误

- 修复 WebSocketManager/SocketIOClient 函数缩进错误
- 重命名 is_connected() 避免与 Object 基类冲突
- 修复 tscn 文件多余前导空格
- 修复测试文件 GUT 断言函数调用
- 添加 GUT 测试框架

scenes/ui/ChatUI.gd

@@ -297,16 +297,17 @@ func _on_chat_error(data: Dictionary) -> void:
 
 	# 3秒后恢复状态
 	var timer := get_tree().create_timer(3.0)
-	timer.timeout.connect(func():
-		_update_connection_status(ChatManager.is_connected())
-	)
+	var 	timeout_callback := func():
+		_update_connection_status(ChatManager.is_chat_connected())
+	timer.timeout.connect(timeout_callback)
 
 # 处理连接状态变化
 func _on_connection_state_changed(data: Dictionary) -> void:
-	var state: WebSocketManager.ConnectionState = data.get("state", WebSocketManager.ConnectionState.DISCONNECTED)
+	var state_names := ["DISCONNECTED", "CONNECTING", "CONNECTED", "RECONNECTING", "ERROR"]
+	var state: int = data.get("state", 0)
 
 	match state:
-		WebSocketManager.ConnectionState.CONNECTED:
+		2:  # CONNECTED
 			_update_connection_status(true)
 		_:
 			_update_connection_status(false)