fix: interview 页面 22x ReferenceError + 引力值明细追加余额栏

interview.vue: 上次会话修改时丢失了 timerSeconds/timerInterval 两个 let 声明
（它们在 git 历史里 d8a7872 时本和 onMounted 同段定义），导致页面渲染时
20+ 次 'ReferenceError: timerSeconds is not defined' 刷屏、对话框/计时器
被白屏错误覆盖。补回两行声明即可还原，无其它改动。

user.vue: 引力值明细每行除金额外追加变动后「余额 N」尾列（schema 中 balance
字段已记录，仅前端未展示）。.detail-item-right 容器纵向堆叠金额+小字余额。

zhiyin-app/src/pages/interview/interview.vue

@@ -193,6 +193,8 @@ function initRecorder() {
   // #endif
 }
 
+let timerSeconds = 0
+let timerInterval = null
 let MAX_QUESTIONS = 10
 const progressPercent = computed(() => Math.min((answeredCount.value / MAX_QUESTIONS) * 100, 100))
 const formatTime = computed(() => {

zhiyin-app/src/pages/user/user.vue

@@ -172,9 +172,12 @@
               <text class="detail-item-desc">{{ tx.description }}</text>
               <text class="detail-item-time">{{ formatTime(tx.createdAt) }}</text>
             </view>
-            <text :class="['detail-item-amount', tx.amount > 0 ? 'amount-positive' : 'amount-negative']">
-              {{ tx.amount > 0 ? '+' : '' }}{{ tx.amount }}
-            </text>
+            <view class="detail-item-right">
+              <text :class="['detail-item-amount', tx.amount > 0 ? 'amount-positive' : 'amount-negative']">
+                {{ tx.amount > 0 ? '+' : '' }}{{ tx.amount }}
+              </text>
+              <text class="detail-item-balance">余额 {{ tx.balance }}</text>
+            </view>
           </view>
         </scroll-view>
         <view v-if="gravityTxTotalPages > 1" class="detail-pagination">
@@ -472,7 +475,9 @@ const doLogout = () => {
 .detail-item-left { display: flex; flex-direction: column; gap: 4rpx; flex: 1; min-width: 0; }
 .detail-item-desc { font-size: 26rpx; color: var(--color-text); font-weight: 500; }
 .detail-item-time { font-size: 20rpx; color: #9CA3AF; }
-.detail-item-amount { font-size: 30rpx; font-weight: 700; flex-shrink: 0; margin-left: 16rpx; }
+.detail-item-amount { font-size: 30rpx; font-weight: 700; }
+.detail-item-right { display: flex; flex-direction: column; align-items: flex-end; gap: 4rpx; flex-shrink: 0; margin-left: 16rpx; }
+.detail-item-balance { font-size: 20rpx; color: #9CA3AF; font-weight: 400; }
 .amount-positive { color: #10B981; }
 .amount-negative { color: #EF4444; }
 .detail-pagination { display: flex; align-items: center; justify-content: center; gap: 24rpx; width: 100%; margin-top: 8rpx; }