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/(public)/dashboard/page.tsx

@@ -11,6 +11,7 @@ import {
   UserPayment,
 } from '@/lib/api';
 import toast from 'react-hot-toast';
+import { CardListSkeleton } from '@/components/ui/Skeleton';
 
 import OverviewTab from './components/OverviewTab';
 import TicketsTab from './components/TicketsTab';
@@ -104,9 +105,7 @@ export default function DashboardPage() {
 
         {/* Tab content */}
         {loading ? (
-          <div className="flex justify-center py-12">
-            <div className="h-8 w-8 animate-spin rounded-full border-b-2 border-primary-yellow" />
-          </div>
+          <CardListSkeleton count={3} />
         ) : (
           <>
             {activeTab === 'overview' && (