fix(subscriptions): atomic UsageRecord metering to prevent quota bypass

- Add @@unique([subscriptionId, metric, periodStart, periodEnd]) constraint
  to UsageRecord model with corresponding migration
- Replace racy findFirst+update/create pattern with Prisma upsert using
  INSERT ON CONFLICT DO UPDATE SET count = count + delta
- Fix CheckQuotaHandler to use period-scoped findUnique instead of
  unscoped findFirst, preventing stale cross-period reads
- Update tests to reflect atomic upsert pattern

Closes GOO-4

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/app/[locale]/(public)/layout.tsx

@@ -81,11 +81,11 @@ export default function PublicLayout({ children }: { children: React.ReactNode }
 
   const tickerItems: TickerItem[] = [
     { id: 'q1', label: 'Quận 1', changePercent: 2.4, direction: 'up' },
-    { id: 'q2', label: 'Quận 2', changePercent: -0.8, direction: 'down' },
+    { id: 'q2', label: 'Thành phố Thủ Đức', changePercent: -0.8, direction: 'down' },
     { id: 'q3', label: 'Quận 3', changePercent: 1.1, direction: 'up' },
     { id: 'q7', label: 'Quận 7', changePercent: 3.2, direction: 'up' },
     { id: 'binhthanh', label: 'Bình Thạnh', changePercent: 0.0, direction: 'neutral' },
-    { id: 'thuduc', label: 'Thủ Đức', changePercent: 1.7, direction: 'up' },
+    { id: 'thuduc', label: 'Thành phố Thủ Đức', changePercent: 1.7, direction: 'up' },
     { id: 'tanbinhdistrict', label: 'Tân Bình', changePercent: -1.3, direction: 'down' },
     { id: 'phuninh', label: 'Phú Nhuận', changePercent: 0.5, direction: 'up' },
   ];