fix: resolve quality audit issues

- utils.js: force UTC+8 output to match MySQL timezone on SCF
- admin subscriptions: return stats (plan counts + revenue) in response
- admin devices: implement keyword search filter
- device-detail: fix binding history field names (bind_time/unbind_time/bind_status)
- user-detail: fix treatment time field (start_time not started_at)
- dashboard: show actual mode per treatment, use sub_stats from dashboard API

admin-console/src/pages/user-detail/index.vue

@@ -67,7 +67,7 @@
         </view>
         <view class="t-body">
           <view class="t-row" v-for="(t, idx) in user.recent_treatments" :key="idx">
-            <text class="t-td flex2">{{ formatDate(t.started_at) }}</text>
+            <text class="t-td flex2">{{ formatDate(t.start_time) }}</text>
             <text class="t-td flex1">{{ Math.floor((t.total_duration_ms || 0) / 60000) }}分钟</text>
             <text class="t-td flex2">{{ t.device_id || '-' }}</text>
           </view>