perf: 清理无界缓存、合并收益走势查询、补齐组合索引并优化前端定时器/图片加载

- 移除只写不读的 verifyCodeCache（无界内存增长）

- 大神收益走势由 20 次逐日/逐周/逐月查询改为 3 次 GROUP BY 聚合

- 派单池地理编码改为并行，避免串行等待外部接口

- 补齐 orders/activities/participants/user_notifications/finance/withdrawals/posts 组合索引；修复 withdrawals 使用不存在 created_at 的失效索引

- 数据库连接池支持 MYSQL_CONNECTION_LIMIT/MYSQL_QUEUE_LIMIT

- 首页/弹窗定时器卸载清理，活动列表参与者按活动 id 查询，大厅组局按页取数，图片 lazy-load

- 121 套件/792 用例全绿；已部署并验证新索引与 9ms 走势查询

pwuniapp/pages/community/index.vue

@@ -129,6 +129,7 @@
               v-for="(img, idx) in post.images"
               :key="idx"
               class="post-img"
+              lazy-load
               :src="img"
               mode="aspectFill"
               @click.stop="previewImage(post.images, idx)"

pwuniapp/pages/expert/hall.vue

@@ -397,8 +397,9 @@ const loadHallData = async () => {
         }
       }).catch(() => {}),
 
-      getActivities().then((list) => {
-        const arr = Array.isArray(list) ? list : [];
+      getActivities({ page: 1, pageSize: 20 }).then((res) => {
+        // 大厅只展示最近 5 个可报名组局，按页取数避免每 30 秒拉全量活动与参与者
+        const arr = Array.isArray(res) ? res : (res && Array.isArray(res.list) ? res.list : []);
         nearbyActivities.value = arr
           .filter((a) => a && (a.status === 'RECRUITING' || a.status === '招募中'))
           .slice(0, 5);

pwuniapp/pages/index/index.vue

@@ -128,7 +128,7 @@
         >
           <!-- 封面图构图优化：高保真黄金比例与底部流光渐变 -->
           <view class="card-cover-wrap">
-            <image class="card-cover" :src="expert.avatar" mode="aspectFill" />
+            <image class="card-cover" :src="expert.avatar" mode="aspectFill" lazy-load />
             <view class="cover-gradient"></view>
             
             <view class="status-tag" :class="expert.isOnline ? 'online' : 'offline'">
@@ -489,6 +489,15 @@ onShow(() => {
 
 onUnmounted(() => {
   uni.$off('theme-change', onThemeChanged);
+  if (searchTimer) {
+    clearTimeout(searchTimer);
+    searchTimer = null;
+  }
+  if (matchTimer) {
+    clearTimeout(matchTimer);
+    matchTimer = null;
+  }
+  matchSeq += 1;
   try { if (homeVoiceAudio) { homeVoiceAudio.destroy(); homeVoiceAudio = null; } } catch (_) {}
 });