Feature: Add 24-hour cleanup for incomplete orders and update status display

- Create cleanupOrders utility to delete pending orders older than 24 hours
- Update admin notifications to only count recent pending orders (< 24h old)
- Automatically call cleanup when customer initiates checkout
- Change status display from "PENDING" to "Waiting payment" for customer-facing views
- Update both customer account page and admin orders page with new status label
- Incomplete orders automatically purged, reducing admin clutter

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/app/account/page.tsx

@@ -13,6 +13,7 @@ function formatPrice(cents: number) {
 function statusLabel(status: string) {
   if (status === 'PAID') return 'Confirmed';
   if (status === 'FAILED') return 'Failed';
+  if (status === 'PENDING') return 'Waiting payment';
   return 'Processing';
 }