first commit

frontend/app/main/loading.tsx

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+import { LoadingSpinner } from "ikoncomponents";
+
+// App Router renders this as the Suspense fallback inside <main> while navigating
+// between menu items, so the sidebar stays put and only the content shows a spinner.
+export default function Loading() {
+  return (
+    <div className="flex h-[60vh] w-full items-center justify-center">
+      <LoadingSpinner />
+    </div>
+  );
+}