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)/components/NextEventSection.tsx

@@ -5,6 +5,7 @@ import Link from 'next/link';
 import { useLanguage } from '@/context/LanguageContext';
 import { eventsApi, Event } from '@/lib/api';
 import { formatPrice, formatDateLong, formatTime } from '@/lib/utils';
+import { FeaturedEventSkeleton } from '@/components/ui/Skeleton';
 import { CalendarIcon, MapPinIcon, ClockIcon } from '@heroicons/react/24/outline';
 
 interface NextEventSectionProps {
@@ -51,11 +52,7 @@ export default function NextEventSection({ initialEvent }: NextEventSectionProps
     : '';
 
   if (loading) {
-    return (
-      <div className="text-center py-12">
-        <div className="animate-spin w-8 h-8 border-4 border-primary-yellow border-t-transparent rounded-full mx-auto" />
-      </div>
-    );
+    return <FeaturedEventSkeleton />;
   }
 
   if (!nextEvent) {