fix(退货审批): 跳过审批数量为空或小于等于0的商品

在审批商品循环中添加检查，当审批数量无效时跳过处理，避免潜在的空指针异常

agileboot-domain/src/main/java/com/agileboot/domain/shop/approval/ReturnApprovalApplicationService.java

@@ -346,6 +346,9 @@ public class ReturnApprovalApplicationService {
         List<ApprovalGoodsCellEntity> addApprovalGoodsCellList = new ArrayList<>();
 
         for (ApprovalGoodsEntity approvalGoodsCommand : approvalGoodsCommands) {
+            if (approvalGoodsCommand.getApprovalQuantity() == null || approvalGoodsCommand.getApprovalQuantity().compareTo(0) <= 0) {
+                continue;
+            }
             ApprovalGoodsEntity approvalGoods = approvalGoodsList.stream()
                     .filter(g -> g.getApprovalGoodsId().equals(approvalGoodsCommand.getApprovalGoodsId())).findFirst().orElse(null);
             if (approvalGoods == null) {