feat(web): Metrics Strip 自動處置率 + MTTR 真實計算

- autoRemediationRate: resolved+closed / total incidents
- mttrAvg: 平均 (updated_at - created_at) 分鐘/小時
- 替換原本的 '--' 靜態值

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/app/[locale]/page.tsx

@@ -43,6 +43,26 @@ export default function Home({ params }: { params: { locale: string } }) {
     enablePolling: true,
   })
 
+  // Metrics Strip 計算
+  const autoRemediationRate = (() => {
+    if (!incidents || incidents.length === 0) return '--'
+    const resolved = incidents.filter(i => i.status === 'resolved' || i.status === 'closed').length
+    if (resolved === 0) return '0%'
+    return `${((resolved / incidents.length) * 100).toFixed(0)}%`
+  })()
+
+  const mttrAvg = (() => {
+    if (!incidents || incidents.length === 0) return '--'
+    const resolved = incidents.filter(i => i.updated_at && (i.status === 'resolved' || i.status === 'closed'))
+    if (resolved.length === 0) return '--'
+    const avgMs = resolved.reduce((sum, i) => {
+      return sum + (new Date(i.updated_at).getTime() - new Date(i.created_at).getTime())
+    }, 0) / resolved.length
+    const mins = Math.round(avgMs / 60000)
+    if (mins < 60) return `${mins}m`
+    return `${(mins / 60).toFixed(1)}h`
+  })()
+
   return (
     <AppLayout locale={locale} showBackground={false}>
     <div style={{
@@ -69,8 +89,8 @@ export default function Home({ params }: { params: { locale: string } }) {
           { label: tDashboard('activeIncidents'), value: incidents?.length ?? '--', sub: incidents?.filter((i) => i.severity === 'P0').length ? `+${incidents.filter((i) => i.severity === 'P0').length} P0` : tDashboard('stable') },
           { label: tDashboard('serviceHealth'), value: `${pulseMetrics?.length ?? '--'}/${pulseMetrics?.length ?? '--'}`, sub: tDashboard('normal') },
           { label: tDashboard('todayIncidents'), value: incidents?.length ?? '--', sub: '' },
-          { label: tDashboard('autoRemediationRate'), value: '--', sub: '' },
-          { label: tDashboard('mttrAvg'), value: '--', sub: '' },
+          { label: tDashboard('autoRemediationRate'), value: autoRemediationRate, sub: '' },
+          { label: tDashboard('mttrAvg'), value: mttrAvg, sub: '' },
         ].map((m, i, arr) => (
           <div key={i} style={{
             flex: 1,