Shadcn Guideline: Skeleton — Use Skeleton for loading. Description: Skeleton component for loading placeholders. Do: Skeleton matching content layout. Don't: Spinner for content loading. Good Example: <Skeleton className="h-4 w-[200px]"/>. Bad Example: <Spinner/> for card loading. Severity: Medium. Docs: https://ui.shadcn.com/docs/components/skeleton.