🐛 fix(exam): 修复盈亏率表头显示异常问题

- 移除盈亏率表头中多余的数字"23423342424"，恢复正确显示"盈亏率"文本

src/client/mobile/components/Exam/ExamCard.tsx

@@ -347,7 +347,7 @@ export default function ExamCard() {
             <div>持币</div>
             <div>价格</div>
             <div>收益(元)</div>
-            <div>盈亏率23423342424</div>
+            <div>盈亏率</div>
           </div>
 
           {/* 表格内容 */}