byType was a hardcoded object keyed by the built-in node kinds. With
the registry, kinds can come from @pascal-app/nodes (or future
plugins) — so byType now wraps a Map via a Proxy that auto-creates an
empty Set the first time any kind is touched.
Built-in kinds are still pre-seeded at module init so the fast path
(no Proxy trap) is preserved. clear() iterates the backing Map.
useRegistry's `type` parameter widens from `keyof typeof byType` to
`KnownNodeKind | (string & {})` — preserves autocomplete for
built-ins while accepting plugin-supplied kinds.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
