Content-shaped skeleton placeholder — matte graphite blocks crossed by a single cool-white light pass (heat-pass timing, not a conveyor). Card / text / circle / rect presets compose to prefigure any layout; @property-driven, zero dependencies, role=status + aria-busy, gentle opacity breathe under reduced motion.
pnpm dlx shadcn@latest add "https://crucibleui.com/r/billet.json"