feat(docs): replace workshop with component catalog (#73)

## Summary

Replace the standalone React workshop with a Blume-native component
catalog that keeps live examples, installation guidance, composition
contracts, and API reference on each component page. Align the source
registry with shadcn installation and theming conventions.

## Catalog

```text
/components
  |-- Flows: connection, host connection, host lifecycle, domain
  |-- Components: records, record card, provider mark, verification
  `-- Registry: DNS table, operation, status, provider mark, copy value, async state
```

- Interactive package previews include Light/Dark plus seven theme
presets.
- Browser validation now runs against the docs server instead of a
separate Vite workshop.
- Registry items declare shadcn primitives through
`registryDependencies` and accept native props, `className`, and
`data-slot`.

## Screenshot

![DomainKit DNS table registry
preview](https://scratchpad.arya.sh/f/01a05894-5ec9-7a18-b5e4-ad4de3a53294/domainkit-registry-preview.png)

## Validation

- `bun run --filter @domainkit/react typecheck`
- `bun run --filter @domainkit/react test` - 68 passed
- `bun run --filter @domainkit/react test:browser` - 5 passed
- `bun run --cwd apps/docs registry:validate` - 6 items
- `bun run --cwd apps/docs registry:check` - clean shadcn install,
TypeScript, and Vite build
- `bunx blume check --isolated --strict`
- `bunx blume build --isolated` - 49 pages
- `bun run --cwd apps/docs audit --strict` - 2,736 checks, no findings
- `bun run format:check`
- `git diff --check`