Replace spinners with skeleton loading states for faster perceived UX.

Add reusable Skeleton components and route-level loading files across public pages and admin lists so layouts stay stable while data loads.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/app/admin/events/[id]/page.tsx

@@ -8,6 +8,7 @@ import { ticketsApi, emailsApi, adminApi, paymentsApi, siteSettingsApi, Ticket }
 import { formatDateLong, formatDateCompact, formatTime } from '@/lib/utils';
 import Card from '@/components/ui/Card';
 import Button from '@/components/ui/Button';
+import { Skeleton, TableSkeleton } from '@/components/ui/Skeleton';
 import { Dropdown, DropdownItem, AdminMobileStyles } from '@/components/admin/MobileComponents';
 import {
   ArrowLeftIcon,
@@ -420,8 +421,12 @@ export default function AdminEventDetailPage() {
 
   if (loading) {
     return (
-      <div className="flex items-center justify-center py-12">
-        <div className="animate-spin w-8 h-8 border-4 border-primary-yellow border-t-transparent rounded-full" />
+      <div>
+        <div className="flex items-center justify-between mb-6">
+          <Skeleton className="h-8 w-64" />
+          <Skeleton className="h-10 w-36 rounded-btn hidden md:block" />
+        </div>
+        <TableSkeleton rows={5} cols={4} />
       </div>
     );
   }