安全：增加测试批次原子清理

shierfeng-fastapi-backend/module_business/dao/test_batch_dao.py

@@ -145,6 +145,10 @@ class TestBatchDao:
                 ]
             )
 
+    @classmethod
+    async def delete_batch_users(cls, db: AsyncSession, batch_id: int) -> None:
+        await db.execute(delete(BizTestBatchUser).where(BizTestBatchUser.batch_id == batch_id))
+
     @classmethod
     async def count_owned_rows(cls, db: AsyncSession, batch_id: int) -> dict[str, int]:
         counts: dict[str, int] = {}