feat: 为奖励详情添加缩略图字段

@@ -93,7 +93,8 @@ const reward = ref({
     applicable_stores: [],
     redeem_rules: [],
     usage_rules: [],
-    can_redeem: false
+    can_redeem: false,
+    thumbnail: ''
 });
 
 /**
@@ -117,7 +118,8 @@ const fetchCouponDetail = async () => {
                 applicable_stores: response.data.applicable_stores || [],
                 redeem_rules: response.data.redeem_rules || [],
                 usage_rules: response.data.usage_rules || [],
-                can_redeem: response.data.can_redeem || false
+                can_redeem: response.data.can_redeem || false,
+                thumbnail: response.data.thumbnail || ''
             };
         }
     } catch (error) {