feat(ops): 看板上应用指标阈值显示

- 在OpsDashboard中加载阈值配置
- 在OpsDashboardHeader中根据阈值判断指标是否超标
- 超出阈值的指标显示为红色（SLA低于阈值也显示红色）
- 用Icon组件替换emoji表情

frontend/src/views/admin/ops/OpsDashboard.vue

@@ -24,6 +24,7 @@
         :query-mode="queryMode"
         :loading="loading"
         :last-updated="lastUpdated"
+        :thresholds="metricThresholds"
         @update:time-range="onTimeRangeChange"
         @update:platform="onPlatformChange"
         @update:group="onGroupChange"
@@ -75,7 +76,7 @@
       <OpsAlertEventsCard v-if="opsEnabled && !(loading && !hasLoadedOnce)" />
 
       <!-- Settings Dialog -->
-      <OpsSettingsDialog :show="showSettingsDialog" @close="showSettingsDialog = false" @saved="fetchData" />
+      <OpsSettingsDialog :show="showSettingsDialog" @close="showSettingsDialog = false" @saved="onSettingsSaved" />
 
       <!-- Alert Rules Dialog -->
       <BaseDialog :show="showAlertRulesCard" :title="t('admin.ops.alertRules.title')" width="extra-wide" @close="showAlertRulesCard = false">
@@ -121,7 +122,8 @@ import {
   type OpsErrorDistributionResponse,
   type OpsErrorTrendResponse,
   type OpsLatencyHistogramResponse,
-  type OpsThroughputTrendResponse
+  type OpsThroughputTrendResponse,
+  type OpsMetricThresholds
 } from '@/api/admin/ops'
 import { useAdminSettingsStore, useAppStore } from '@/stores'
 import OpsDashboardHeader from './components/OpsDashboardHeader.vue'
@@ -314,6 +316,7 @@ const syncQueryToRoute = useDebounceFn(async () => {
 }, 250)
 
 const overview = ref<OpsDashboardOverview | null>(null)
+const metricThresholds = ref<OpsMetricThresholds | null>(null)
 
 const throughputTrend = ref<OpsThroughputTrendResponse | null>(null)
 const loadingTrend = ref(false)
@@ -376,6 +379,11 @@ function onTimeRangeChange(v: string | number | boolean | null) {
   timeRange.value = v as TimeRange
 }
 
+function onSettingsSaved() {
+  loadThresholds()
+  fetchData()
+}
+
 function onPlatformChange(v: string | number | boolean | null) {
   platform.value = typeof v === 'string' ? v : ''
 }
@@ -615,6 +623,9 @@ onMounted(async () => {
     return
   }
 
+  // Load thresholds configuration
+  loadThresholds()
+
   if (adminSettingsStore.opsRealtimeMonitoringEnabled) {
     startQPSSubscription()
   } else {
@@ -626,6 +637,16 @@ onMounted(async () => {
   }
 })
 
+async function loadThresholds() {
+  try {
+    const settings = await opsAPI.getAlertRuntimeSettings()
+    metricThresholds.value = settings.thresholds || null
+  } catch (err) {
+    console.warn('[OpsDashboard] Failed to load thresholds', err)
+    metricThresholds.value = null
+  }
+}
+
 onUnmounted(() => {
   stopQPSSubscription()
   abortDashboardFetch()