feat(order): 设置采购订单类型默认值

- 在PODetailServiceImpl中为采购订单设置默认订单类型
- 确保从Excel导入时订单类型字段正确赋值
- 统一订单类型标识符为"采购订单"

src/main/java/com/xujie/modules/order/service/Impl/PODetailServiceImpl.java

@@ -200,6 +200,7 @@ public class PODetailServiceImpl extends ServiceImpl<PODetailMapper, PODetail> i
                     poHeader.setDestination(excelDTO.getDestination());
                     poHeader.setShipVia(excelDTO.getShipVia());
                     poHeader.setBuyer(excelDTO.getBuyer());
+                    poHeader.setOrderType("采购订单");
 
                     // 设置默认值
                     poHeader.setCurrency("USA");