perf: 全栈查询优化、前端缓存去重与页面可见性优化

后端:
- SQL count 查询统一改用 func.count() 子查询替代 query.count()
- Dashboard/Audit 等页面多次独立查询合并为单次聚合查询
- Provider summary 列表改为批量查询消除 N+1 问题
- DailyStats 逐天循环查询改为 CASE 分桶单次查询
- 使用 load_only() 减少不必要的列加载
- cache_decorator 支持嵌套属性路径解析(dotted vary_by)
- 多个管理/公共端点新增 @cache_result 缓存装饰

前端:
- cache.ts 新增 in-flight 请求复用、dedupedRequest、buildCacheKey
- 大量 API 调用添加前端缓存或去重
- 多个页面定时器在标签页隐藏时暂停、可见时恢复
- Auth 检查从 setInterval 改为 storage + visibilitychange 事件驱动
- 请求竞态防护(requestId 模式)

数据库:
- Usage 表新增 idx_usage_status_user_created 复合索引

frontend/src/views/admin/UserStats.vue

@@ -144,7 +144,7 @@
 </template>
 
 <script setup lang="ts">
-import { ref, computed, onMounted, watch } from 'vue'
+import { ref, computed, onMounted, onUnmounted, watch } from 'vue'
 import { Card, Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui'
 import LineChart from '@/components/charts/LineChart.vue'
 import { LoadingState, TimeRangePicker } from '@/components/common'
@@ -184,6 +184,15 @@ const summaryLoading = ref(false)
 const series = ref<TimeSeriesItem[]>([])
 const comparisonSeries = ref<TimeSeriesItem[]>([])
 const seriesLoading = ref(false)
+let leaderboardRequestId = 0
+let summaryRequestId = 0
+let seriesRequestId = 0
+let leaderboardLoadPromise: Promise<void> | null = null
+let hasPendingLeaderboardLoad = false
+let leaderboardDebounceTimer: ReturnType<typeof setTimeout> | null = null
+let userPanelsLoadPromise: Promise<void> | null = null
+let hasPendingUserPanelsLoad = false
+let userPanelsDebounceTimer: ReturnType<typeof setTimeout> | null = null
 
 function buildTimeRangeParams() {
   return {
@@ -204,6 +213,12 @@ async function loadUsers() {
 }
 
 async function loadLeaderboard() {
+  if (leaderboardLoadPromise) {
+    hasPendingLeaderboardLoad = true
+    return leaderboardLoadPromise
+  }
+  leaderboardLoadPromise = (async () => {
+  const requestId = ++leaderboardRequestId
   leaderboardLoading.value = true
   try {
     const response = await adminApi.getLeaderboardUsers({
@@ -211,46 +226,90 @@ async function loadLeaderboard() {
       metric: metric.value,
       limit: 10
     })
+    if (requestId !== leaderboardRequestId) return
     leaderboard.value = response.items
   } finally {
-    leaderboardLoading.value = false
+    if (requestId === leaderboardRequestId) {
+      leaderboardLoading.value = false
+    }
   }
+  })().finally(() => {
+    leaderboardLoadPromise = null
+    if (hasPendingLeaderboardLoad) {
+      hasPendingLeaderboardLoad = false
+      void loadLeaderboard()
+    }
+  })
+  return leaderboardLoadPromise
 }
 
 async function loadSummary() {
   if (!selectedUserId.value) return
+  const requestId = ++summaryRequestId
   summaryLoading.value = true
   try {
-    userSummary.value = await usageApi.getUsageStats({
+    const summary = await usageApi.getUsageStats({
       ...buildTimeRangeParams(),
       user_id: selectedUserId.value
     })
+    if (requestId !== summaryRequestId) return
+    userSummary.value = summary
   } finally {
-    summaryLoading.value = false
+    if (requestId === summaryRequestId) {
+      summaryLoading.value = false
+    }
   }
 }
 
 async function loadSeries() {
   if (!selectedUserId.value) return
+  const requestId = ++seriesRequestId
   seriesLoading.value = true
   try {
-    series.value = await adminApi.getTimeSeries({
+    const baseParams = {
       ...buildTimeRangeParams(),
       user_id: selectedUserId.value
-    })
-
-    comparisonSeries.value = []
-    if (compareUserId.value && compareUserId.value !== '__none__') {
-      comparisonSeries.value = await adminApi.getTimeSeries({
+    }
+    const shouldCompare = Boolean(compareUserId.value && compareUserId.value !== '__none__')
+    const comparePromise: Promise<TimeSeriesItem[]> = shouldCompare
+      ? adminApi.getTimeSeries({
         ...buildTimeRangeParams(),
         user_id: compareUserId.value
       })
-    }
+      : Promise.resolve([])
+
+    const [primarySeries, compareSeries] = await Promise.all([
+      adminApi.getTimeSeries(baseParams),
+      comparePromise
+    ])
+
+    if (requestId !== seriesRequestId) return
+    series.value = primarySeries
+    comparisonSeries.value = compareSeries
   } finally {
-    seriesLoading.value = false
+    if (requestId === seriesRequestId) {
+      seriesLoading.value = false
+    }
   }
 }
 
+async function loadUserPanels() {
+  if (userPanelsLoadPromise) {
+    hasPendingUserPanelsLoad = true
+    return userPanelsLoadPromise
+  }
+  userPanelsLoadPromise = Promise.all([loadSummary(), loadSeries()])
+    .then(() => undefined)
+    .finally(() => {
+      userPanelsLoadPromise = null
+      if (hasPendingUserPanelsLoad) {
+        hasPendingUserPanelsLoad = false
+        void loadUserPanels()
+      }
+    })
+  return userPanelsLoadPromise
+}
+
 const seriesChartData = computed(() => ({
   labels: series.value.map(item => item.date),
   datasets: [
@@ -284,16 +343,52 @@ const comparisonChartData = computed(() => ({
   ]
 }))
 
-watch([timeRange, metric], loadLeaderboard, { deep: true })
-watch([timeRange, selectedUserId, compareUserId], () => {
-  loadSummary()
-  loadSeries()
-}, { deep: true })
+function scheduleLeaderboardLoad() {
+  if (leaderboardDebounceTimer) {
+    clearTimeout(leaderboardDebounceTimer)
+  }
+  leaderboardDebounceTimer = setTimeout(() => {
+    leaderboardDebounceTimer = null
+    void loadLeaderboard()
+  }, 120)
+}
+
+function scheduleUserPanelsLoad() {
+  if (userPanelsDebounceTimer) {
+    clearTimeout(userPanelsDebounceTimer)
+  }
+  userPanelsDebounceTimer = setTimeout(() => {
+    userPanelsDebounceTimer = null
+    void loadUserPanels()
+  }, 120)
+}
+
+watch([timeRange, metric], scheduleLeaderboardLoad, { deep: true })
+watch([timeRange, selectedUserId, compareUserId], scheduleUserPanelsLoad, { deep: true })
 
 onMounted(async () => {
   await loadUsers()
-  await loadLeaderboard()
-  await loadSummary()
-  await loadSeries()
+  await Promise.all([
+    loadLeaderboard(),
+    loadUserPanels()
+  ])
+})
+
+onUnmounted(() => {
+  if (leaderboardDebounceTimer) {
+    clearTimeout(leaderboardDebounceTimer)
+    leaderboardDebounceTimer = null
+  }
+  if (userPanelsDebounceTimer) {
+    clearTimeout(userPanelsDebounceTimer)
+    userPanelsDebounceTimer = null
+  }
+  hasPendingLeaderboardLoad = false
+  hasPendingUserPanelsLoad = false
+  leaderboardLoadPromise = null
+  userPanelsLoadPromise = null
+  leaderboardRequestId += 1
+  summaryRequestId += 1
+  seriesRequestId += 1
 })
 </script>