style(Rewards): 优化奖励页面样式和排序图标显示

- 为未选中的积分选项添加背景色提高可读性
- 将排序图标从ScreenLittle替换为更直观的TriangleUp/TriangleDown

 <!--
  * @Date: 2025-08-27 17:47:26
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-09-13 16:22:18
+ * @LastEditTime: 2025-09-15 13:03:39
  * @FilePath: /lls_program/src/pages/Rewards/index.vue
  * @Description: 文件描述
 -->
@@ -35,7 +35,7 @@
               'flex-1 py-3 rounded-lg border text-center',
               selectedPoints === option.range
                 ? 'border-blue-500 bg-blue-50 text-blue-500'
-                : 'border-gray-200 text-gray-700'
+                : 'border-gray-200 text-gray-700 bg-gray-50'
             ]">
             <view class="text-center text-xs">
               <view>{{ option.label }}</view>
@@ -47,7 +47,8 @@
           <h3 class="text-lg font-medium">可兑换列表</h3>
           <view class="flex items-center text-gray-500 text-sm" @click="toggleSortOrder">
             <span class="mr-1">{{ sortOrder === 'desc' ? '从高到低排列' : '从低到高排列' }}</span>
-            <ScreenLittle />
+            <TriangleDown v-if="sortOrder === 'desc'" />
+            <TriangleUp v-else />
           </view>
         </view>
         <!-- Rewards list -->
@@ -100,7 +101,7 @@
 <script setup>
 import { ref, computed, onMounted, watch } from 'vue';
 import Taro, { useDidShow } from '@tarojs/taro';
-import { ScreenLittle, Search2, My, ArrowUp, ArrowDown } from '@nutui/icons-vue-taro';
+import { TriangleDown, TriangleUp, Search2, My, ArrowUp, ArrowDown } from '@nutui/icons-vue-taro';
 import BottomNav from '../../components/BottomNav.vue';
 // 导入接口
 import { getUserProfileAPI } from '@/api/user';