feat(pricing): 增加商品参数校验和默认值设置

- 为每个产品增加产品类型和产品 ID 的非空校验
- 为购买数量和数量设置默认值为 1，如果未提供

src/main/java/com/ycwl/basic/pricing/service/impl/PriceCalculationServiceImpl.java

@@ -35,7 +35,21 @@ public class PriceCalculationServiceImpl implements IPriceCalculationService {
         if (request.getProducts() == null || request.getProducts().isEmpty()) {
             throw new PriceCalculationException("商品列表不能为空");
         }
-        
+
+        request.getProducts().forEach(product -> {
+            if (product.getProductType() == null) {
+                throw new PriceCalculationException("商品类型不能为空");
+            }
+            if (product.getProductId() == null) {
+                throw new PriceCalculationException("商品ID不能为空");
+            }
+            if (product.getPurchaseCount() == null) {
+                product.setPurchaseCount(1);
+            }
+            if (product.getQuantity() == null) {
+                product.setQuantity(1);
+            }
+        });
         // 计算商品价格和原价
         PriceDetails priceDetails = calculateProductsPriceWithOriginal(request.getProducts());
         BigDecimal totalAmount = priceDetails.getTotalAmount();