Component catalog expansion

Boundaries

• lib/catalog.ts owns discovery metadata, new-item state, and documentation groups.
• components/ui/* owns backend-agnostic primitives with controlled and uncontrolled APIs.
• components/library/component-preview.tsx owns interactive documentation state.
• components/library/component-workbench.tsx owns copy-ready examples.
• registry.json and component-registry.json own CLI distribution and reuse metadata.

Passes

1. Add explicit new-item metadata and grouped navigation without changing component routes.
2. Add overlay/navigation primitives: Dropdown, Popover, Modal, Sidebar, MobileNav.
3. Add data primitives: Chart and Table.
4. Add previews, exact examples, CLI entries, and generated registry artifacts.

Parity checks

• Existing component URLs and names remain stable.
• A new blue dot appears in both the component index and documentation sidebar.
• Dropdown, Popover, Modal, and Sidebar support keyboard dismissal.
• Sidebar supports controlled open/close and responsive presentation.
• Table exposes semantic table markup; Chart includes an accessible label and data summary.
• Every new catalog slug has a source file, preview, snippet, registry entry, generated JSON, and static route.