Method backup_database

script/btcli.py:505–507

备份数据库（预留）

(self, db_id: int)

    # ============ 预留功能接口 ============
    
    def backup_database(self, db_id: int):
        """备份数据库（预留）"""
        print(Colors.warning("功能开发中..."))
    
    def change_password(self, db_id: int, new_password: str):
        """修改数据库密码（预留）"""