fix(RankingCard): 修复我的排名卡片在没有topRanks时的显示问题

当topRanks为空数组时，我的排名卡片不应显示。添加了条件判断确保只在有topRanks时显示我的排名卡片，并添加了备选显示逻辑。

 <!--
  * @Date: 2025-01-09 00:00:00
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-10-10 10:53:43
+ * @LastEditTime: 2025-10-10 10:56:32
  * @FilePath: /lls_program/src/components/RankingCard.vue
  * @Description: 排行榜卡片组件
 -->
@@ -110,22 +110,41 @@
     </view>
 
     <!-- 我的排名卡片 -->
-    <view v-if="myRank" class="my-rank-section">
+    <view v-if="myRank && topRanks.length" class="my-rank-section">
       <view class="my-rank-content">
         <view class="my-rank-left">
           <view class="my-rank-number">
-            {{ myRank.isNotRanked ? '-' : (myRank.rank > 99 ? '99+' : myRank.rank) }}
+            {{ myRank?.isNotRanked ? '-' : (myRank?.rank > 99 ? '99+' : myRank?.rank) }}
           </view>
           <view class="my-avatar">
             <image :src="myRank.avatar_url || defaultAvatar" class="my-avatar-img" mode="aspectFill" />
           </view>
           <view class="my-family-info">
-            <view class="my-family-name">{{ myRank.name }}</view>
-            <view class="my-leader-name">{{ activeTab === 'support' ? `${myRank.created_by_nickname}个家庭` : `大家长：${myRank.created_by_nickname}` }}</view>
+            <view class="my-family-name">{{ myRank?.name }}</view>
+            <view class="my-leader-name">{{ activeTab === 'support' ? `${myRank?.created_by_nickname}个家庭` : `大家长：${myRank?.created_by_nickname}` }}</view>
           </view>
         </view>
         <view class="my-rank-right">
-          <view class="my-steps">{{ activeTab === 'support' ? formatSupportSteps(myRank.step) : formatStepsForList(myRank.step) }}</view>
+          <view class="my-steps">{{ activeTab === 'support' ? formatSupportSteps(myRank?.step) : formatStepsForList(myRank?.step) }}</view>
+        </view>
+      </view>
+    </view>
+    <view v-else class="my-rank-section">
+      <view class="my-rank-content">
+        <view class="my-rank-left">
+          <view class="my-rank-number">
+            {{ myRank?.isNotRanked ? '-' : (myRank?.rank > 99 ? '99+' : myRank?.rank) }}
+          </view>
+          <view class="my-avatar">
+            <image :src="myRank?.avatar_url || defaultAvatar" class="my-avatar-img" mode="aspectFill" />
+          </view>
+          <view class="my-family-info">
+            <view class="my-family-name">{{ myRank?.name }}</view>
+            <view class="my-leader-name">{{ activeTab === 'support' ? `${myRank?.created_by_nickname}个家庭` : `大家长：${myRank?.created_by_nickname}` }}</view>
+          </view>
+        </view>
+        <view class="my-rank-right">
+          <view class="my-steps">{{ activeTab === 'support' ? formatSupportSteps(myRank?.step) : formatStepsForList(myRank?.step) }}</view>
         </view>
       </view>
     </view>