✨ feat: Add model performance metrics to dashboard

Add a shared `performance-metrics` feature module for perf metric APIs, DTOs, and formatting, then surface global 24h model performance on the dashboard with cards and a top-model table.

Reuse the shared metrics module from pricing model details, remove duplicated perf API/formatting code from pricing, and add localized labels for the new dashboard performance UI.

web/default/src/features/pricing/components/model-perf-badge.tsx

@@ -1,7 +1,10 @@
 import { memo } from 'react'
 import { useTranslation } from 'react-i18next'
 import { cn } from '@/lib/utils'
-import { formatLatency, formatThroughput } from '../lib/mock-stats'
+import {
+  formatLatency,
+  formatThroughput,
+} from '@/features/performance-metrics/lib/format'
 
 export type ModelPerfBadgeData = {
   avg_latency_ms: number