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)/events/[id]/loading.tsx

@@ -0,0 +1,28 @@
+import { Skeleton, ArticleSkeleton } from '@/components/ui/Skeleton';
+
+// Route-level skeleton for the event detail page: back link, banner, article
+// body on the left and the booking card in the sidebar.
+export default function EventDetailLoading() {
+  return (
+    <div className="section-padding">
+      <div className="container-page">
+        <Skeleton className="h-5 w-36" />
+        <div className="mt-6 grid grid-cols-1 lg:grid-cols-3 gap-8">
+          <div className="lg:col-span-2">
+            <ArticleSkeleton withBanner />
+          </div>
+          <div>
+            <div className="bg-white rounded-card shadow-card p-6" aria-hidden="true">
+              <div className="text-center">
+                <Skeleton className="h-4 w-16 mx-auto" />
+                <Skeleton className="mt-3 h-10 w-32 mx-auto" />
+              </div>
+              <Skeleton className="mt-6 h-12 w-full rounded-btn" />
+              <Skeleton className="mt-3 h-4 w-3/4 mx-auto" />
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+}