mysql和oracle库之间来回切换时，需要seata分布式事务保证数据一致性

## Why you need it?
实际业务中需要同时操作mysql和oracle库 两个库的数据，所以需要使用seata的分布式事务保证两个库中数据的准确性、一致性。

## How it could be?
A库mysql，B库oracle。业务需要将A库的数据查询出来，然后写入B库中，写入完B库后再更新A库中该笔数据的状态，使用分布式事务保证数据的准确性、一致性。。

## Other related information
无

Start by locating Seata's database transaction support and documentation for cross-database transactions involving MySQL and Oracle. The issue does not name files, tests, or an entry point, so first determine whether this is an existing capability gap or a new design. Done would require a defined and tested way to preserve consistency across both databases.

Written by the indexing model from the issue text.