feat(frontend): add initial Next.js UI app

components/ui/spinner.tsx

@@ -0,0 +1,16 @@
+import { Loader2Icon } from 'lucide-react'
+
+import { cn } from '@/lib/utils'
+
+function Spinner({ className, ...props }: React.ComponentProps<'svg'>) {
+  return (
+    <Loader2Icon
+      role="status"
+      aria-label="Loading"
+      className={cn('size-4 animate-spin', className)}
+      {...props}
+    />
+  )
+}
+
+export { Spinner }