chore: snapshot before performance optimization

keep-notes/app/(main)/admin/loading.tsx

@@ -0,0 +1,20 @@
+export default function AdminLoading() {
+  return (
+    <div className="space-y-6 animate-pulse">
+      <div>
+        <div className="h-9 w-48 bg-muted rounded-md mb-2" />
+        <div className="h-4 w-72 bg-muted rounded-md" />
+      </div>
+      {[1, 2, 3].map((i) => (
+        <div key={i} className="rounded-lg border border-border bg-white dark:bg-zinc-900 p-6 space-y-4">
+          <div className="h-5 w-40 bg-muted rounded" />
+          <div className="h-px bg-border" />
+          <div className="space-y-3">
+            <div className="h-4 w-full bg-muted rounded" />
+            <div className="h-4 w-3/4 bg-muted rounded" />
+          </div>
+        </div>
+      ))}
+    </div>
+  )
+}