refactor: 重构消息类型的初始化逻辑，新增各消息类型的构造函数以提高代码可读性和可维护性

message/video.go

@@ -25,10 +25,14 @@ type VideoMessageData struct {
 
 func init() {
 	RegisterMessageType(TypeVideo, func() CQMessage {
-		return &VideoMessage{Type: TypeVideo}
+		return NewVideoMessage()
 	})
 }
 
+func NewVideoMessage() *VideoMessage {
+	return &VideoMessage{Type: TypeVideo}
+}
+
 func (msg *VideoMessage) SetData(data json.RawMessage) error {
 	return json.Unmarshal(data, &msg.Data)
 }