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/loading.tsx

@@ -0,0 +1,20 @@
+import { Skeleton, EventGridSkeleton } from '@/components/ui/Skeleton';
+
+// Route-level skeleton shown during navigation while the server fetches the
+// event list. Mirrors the EventsClient shell: title, filter tabs, card grid.
+export default function EventsLoading() {
+  return (
+    <div className="section-padding">
+      <div className="container-page">
+        <Skeleton className="h-10 w-64" />
+        <div className="mt-8 flex gap-2">
+          <Skeleton className="h-10 w-32 rounded-btn" />
+          <Skeleton className="h-10 w-28 rounded-btn" />
+        </div>
+        <div className="mt-8">
+          <EventGridSkeleton count={6} />
+        </div>
+      </div>
+    </div>
+  );
+}