fix: 移除商户中心商户查询兜底逻辑

src/Application/TakeoutSaaS.Application/App/Merchants/Handlers/GetCurrentMerchantCenterQueryHandler.cs

@@ -57,7 +57,7 @@ public sealed class GetCurrentMerchantCenterQueryHandler(
         }
 
         // 4. 解析当前用户可访问商户
-        var merchantId = await ResolveMerchantIdAsync(currentUser.MerchantId, currentTenantId, cancellationToken);
+        var merchantId = ResolveMerchantId(currentUser.MerchantId);
 
         // 5. 读取商户主体与租户信息
         var merchant = await merchantRepository.FindByIdAsync(merchantId, currentTenantId, cancellationToken)
@@ -87,29 +87,19 @@ public sealed class GetCurrentMerchantCenterQueryHandler(
     }
 
     /// <summary>
-    /// 解析当前用户对应的商户标识。
+    /// 解析当前用户绑定的商户标识。
     /// </summary>
     /// <param name="currentUserMerchantId">当前用户绑定的商户 ID。</param>
-    /// <param name="tenantId">当前租户 ID。</param>
-    /// <param name="cancellationToken">取消标记。</param>
     /// <returns>商户 ID。</returns>
-    private async Task<long> ResolveMerchantIdAsync(long? currentUserMerchantId, long tenantId, CancellationToken cancellationToken)
+    private static long ResolveMerchantId(long? currentUserMerchantId)
     {
-        // 1. 优先使用用户显式绑定的商户
+        // 1. 严格使用用户绑定商户
         if (currentUserMerchantId is > 0)
         {
             return currentUserMerchantId.Value;
         }
 
-        // 2. 兜底读取租户下最新商户
-        var merchants = await merchantRepository.SearchAsync(tenantId, status: null, cancellationToken);
-        var merchantId = merchants.FirstOrDefault()?.Id;
-        if (!merchantId.HasValue || merchantId.Value <= 0)
-        {
-            throw new BusinessException(ErrorCodes.NotFound, "当前租户尚未创建商户信息");
-        }
-
-        // 3. 返回商户标识
-        return merchantId.Value;
+        // 2. 未绑定商户直接拒绝访问
+        throw new BusinessException(ErrorCodes.Forbidden, "当前用户未绑定商户，禁止访问商户中心");
     }
 }