feat(order): 添加价格预览模式支持

- 在VLOG商品价格计算中添加previewOnly标志
- 在普通商品价格计算中添加previewOnly标志
- 确保价格查询时不实际使用优惠券
- 支持仅查询最终价格和原始价格的功能

src/main/java/com/ycwl/basic/biz/OrderBiz.java

@@ -118,6 +118,7 @@ public class OrderBiz {
                 vlogProductItem.setScenicId(scenicId.toString());
                 vlogCalculationRequest.setProducts(Collections.singletonList(vlogProductItem));
                 vlogCalculationRequest.setFaceId(priceObj.getFaceId());
+                vlogCalculationRequest.setPreviewOnly(true); // 仅查询价格，不实际使用优惠
                 PriceCalculationResult vlogCalculationResult = iPriceCalculationService.calculatePrice(vlogCalculationRequest);
                 priceObj.setPrice(vlogCalculationResult.getFinalAmount());
                 priceObj.setSlashPrice(vlogCalculationResult.getOriginalAmount());
@@ -138,6 +139,7 @@ public class OrderBiz {
                     calculationRequest.setUserId(face.getMemberId());
                 }
                 calculationRequest.setFaceId(goodsId);
+                calculationRequest.setPreviewOnly(true); // 仅查询价格，不实际使用优惠
                 PriceCalculationResult priceCalculationResult = iPriceCalculationService.calculatePrice(calculationRequest);
                 priceObj.setPrice(priceCalculationResult.getFinalAmount());
                 priceObj.setSlashPrice(priceCalculationResult.getOriginalAmount());