refactor: 统一业务异常处理，标准化结果码和错误响应

1.  新增并完善ResultCode枚举，补充标准HTTP状态码对应的业务状态码
2.  重构BusinessException，新增基于ResultCode的构造函数和ThrowIf扩展方法
3.  替换所有硬编码的HTTP状态码为统一的ResultCode枚举
4.  优化全局异常中间件，根据业务状态码映射对应HTTP状态码并规范化JSON响应
5.  修复OssImageHelper和AutoDotCodeConsumer中的OSS文件处理逻辑
6.  新增用户答题快照实体类
7.  清理废弃的宠物模块迁移脚本

QYZH.InteractiveMagazine.Service/WxMallService.cs

@@ -1,6 +1,7 @@
 using Microsoft.Extensions.Logging;
 using QYZH.InteractiveMagazine.IService;
 using QYZH.InteractiveMagazine.Models.Common;
+using QYZH.InteractiveMagazine.Models.Dto;
 using QYZH.InteractiveMagazine.Models.Dto.Bag;
 using QYZH.InteractiveMagazine.Models.Dto.Mall;
 using QYZH.InteractiveMagazine.Models.Dto.Points;
@@ -187,10 +188,10 @@ public class WxMallService(
             userId, input.ProductId, input.Quantity);
 
         if (input.ProductId <= 0)
-            throw new BusinessException("商品Id无效", 400);
+            throw new BusinessException("商品Id无效", ResultCode.BAD_REQUEST);
 
         if (input.Quantity <= 0)
-            throw new BusinessException("兑换数量必须大于0", 400);
+            throw new BusinessException("兑换数量必须大于0", ResultCode.BAD_REQUEST);
 
         // 查询商品
         var product = await exchangeRecordRepository.Context.Queryable<Product>()
@@ -198,7 +199,7 @@ public class WxMallService(
             .FirstAsync();
 
         if (product == null)
-            throw new BusinessException("商品不存在或已下架", 404);
+            throw new BusinessException("商品不存在或已下架", ResultCode.NOT_FOUND);
 
         var totalCost = product.Price * input.Quantity;
 
@@ -404,24 +405,24 @@ public class WxMallService(
         logger.LogInformation("使用背包物品，UserId: {UserId}, BagItemId: {BagItemId}", userId, input.BagItemId);
 
         if (input.BagItemId <= 0)
-            throw new BusinessException("背包物品Id无效", 400);
+            throw new BusinessException("背包物品Id无效", ResultCode.BAD_REQUEST);
 
         var bagItem = await exchangeRecordRepository.Context.Queryable<UserBag>()
             .Where(b => b.Id == input.BagItemId && b.UserId == userId && b.Status == (int)UserBagStatusEnum.Available)
             .FirstAsync();
 
         if (bagItem == null)
-            throw new BusinessException("背包物品不存在", 404);
+            throw new BusinessException("背包物品不存在", ResultCode.NOT_FOUND);
 
         if (bagItem.Quantity <= 0)
-            throw new BusinessException("物品数量不足", 400);
+            throw new BusinessException("物品数量不足", ResultCode.BAD_REQUEST);
 
         switch (bagItem.ItemType)
         {
             case "MakeUpCard":
                 return await UseMakeUpCardAsync(userId, bagItem, input);
             default:
-                throw new BusinessException($"不支持使用该类型物品: {bagItem.ItemType}", 400);
+                throw new BusinessException($"不支持使用该类型物品: {bagItem.ItemType}", ResultCode.BAD_REQUEST);
         }
     }
 
@@ -431,15 +432,15 @@ public class WxMallService(
     private async Task<UseItemOutput> UseMakeUpCardAsync(long userId, UserBag bagItem, UseItemInput input)
     {
         if (string.IsNullOrEmpty(input.TargetDate))
-            throw new BusinessException("请指定补签日期", 400);
+            throw new BusinessException("请指定补签日期", ResultCode.BAD_REQUEST);
 
         if (!DateTime.TryParse(input.TargetDate, out var targetDate))
-            throw new BusinessException("日期格式无效", 400);
+            throw new BusinessException("日期格式无效", ResultCode.BAD_REQUEST);
 
         targetDate = targetDate.Date;
 
         if (targetDate >= DateTime.Now.Date)
-            throw new BusinessException("只能补签过去的日期", 400);
+            throw new BusinessException("只能补签过去的日期", ResultCode.BAD_REQUEST);
 
         // 调用签到服务执行补签（内部会检查并扣减补签卡）
         var checkInResult = await checkInService.MakeUpCheckInAsync(userId, targetDate);
@@ -467,7 +468,7 @@ public class WxMallService(
             .FirstAsync();
 
         if (pet == null)
-            throw new BusinessException("您还没有宠物", 404);
+            throw new BusinessException("您还没有宠物", ResultCode.NOT_FOUND);
 
         if (input.SkinId == 0)
         {
@@ -488,7 +489,7 @@ public class WxMallService(
             .FirstAsync();
 
         if (skin == null)
-            throw new BusinessException("皮肤不存在", 404);
+            throw new BusinessException("皮肤不存在", ResultCode.NOT_FOUND);
 
         // 校验背包中是否拥有该皮肤（通过 MetaData 中的 SkinId 判断）
         var hasSkin = await exchangeRecordRepository.Context.Queryable<UserBag>()
@@ -499,7 +500,7 @@ public class WxMallService(
         var owned = hasSkin.Any(b => GetSkinIdFromMetaData(b.MetaData) == input.SkinId);
 
         if (!owned)
-            throw new BusinessException("您尚未拥有该皮肤，请先兑换", 400);
+            throw new BusinessException("您尚未拥有该皮肤，请先兑换", ResultCode.BAD_REQUEST);
 
         // 换肤
         await exchangeRecordRepository.Context.Updateable<UserPet>()