fix(Rewards): 移除商户名称的默认值显示

 <!--
  * @Date: 2025-08-27 17:47:26
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-09-17 13:55:54
+ * @LastEditTime: 2025-09-17 17:16:33
  * @FilePath: /lls_program/src/pages/Rewards/index.vue
  * @Description: 文件描述
 -->
@@ -69,7 +69,7 @@
               <image :src="reward.thumbnail" class="w-16 h-16 rounded-lg mr-4 flex-shrink-0" mode="aspectFill" />
               <view class="flex-1 min-w-0">
                 <view class="font-medium text-base">{{ reward.title }}</view>
-                <view class="text-gray-500 text-sm mt-1">{{ reward.merchant_name || '商户' }}</view>
+                <view class="text-gray-500 text-sm mt-1">{{ reward.merchant_name }}</view>
               </view>
               <view class="ml-4 px-4 py-2 bg-blue-500 text-white rounded-lg text-sm flex-shrink-0"
                 @click="goToRewardDetail(reward)">