refactor: 移除SocketIOClient并更新认证场景

- 移除SocketIOClient.gd及.uid文件
- 更新ChatManager以适配新的架构
- 添加认证UI图片资源和背景音乐
- 优化AuthScene布局和配置
- 更新MainScene和项目配置

_Core/managers/ChatManager.gd

@@ -233,7 +233,7 @@ func send_chat_message(content: String, scope: String = "local") -> void:
 
 	# 构建消息数据
 	var message_data := {
-		"t": "chat",
+		"type": "chat",
 		"content": content,
 		"scope": scope
 	}
@@ -284,7 +284,7 @@ func update_player_position(x: float, y: float, map_id: String) -> void:
 		return
 
 	var position_data := {
-		"t": "position",
+		"type": "position",
 		"x": x,
 		"y": y,
 		"mapId": map_id