refactor(lst): added side bar plus dummy menus

frontend/src/components/ui/skeleton.tsx

@@ -0,0 +1,7 @@
+import {cn} from "../../lib/utils";
+
+function Skeleton({className, ...props}: React.ComponentProps<"div">) {
+    return <div data-slot="skeleton" className={cn("bg-primary/10 animate-pulse rounded-md", className)} {...props} />;
+}
+
+export {Skeleton};