feat(usage): refactor dashboard frontend with shadcn/ui components, skeleton states, and dark-theme charts

src/components/ui/skeleton.tsx

@@ -0,0 +1,7 @@
+import { cn } from '@/lib/utils';
+
+function Skeleton({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) {
+  return <div className={cn('bg-muted animate-pulse rounded-md', className)} {...props} />;
+}
+
+export { Skeleton };