Registry structure

1app/                 Documentation website
2components/ui/       Installable component source
3components/library/  Documentation previews
4lib/                 Shared utilities and catalogs
5public/r/            Generated registry payloads
6registry.json        Registry source of truth
7components.json      Local shadcn configuration

When adding an installable component:

Add its source to components/ui.
Declare the item and dependencies in registry.json.
Add its documentation metadata to lib/catalog.ts.
Add a preview and example source.
Build and validate the registry.