
- Added `appKey` field to `PayAppDO` to store application secret key. - Updated `PayOrderService` interface to include `appKey` parameter in `getOrder` and `createOrder` methods. - Implemented `getOrder` method in `PayOrderServiceImpl` to fetch `PayOrderDO` using `appKey` and `merchantOrderId`. - Added necessary validation and exception handling for `appKey` in `PayOrderServiceImpl`.