Introduces the @pascal-app/core/registry surface that future node-bundle
packages (and external plugins) will use to register node kinds with the
host. No runtime behavior changes — registry is empty until subsequent
PRs populate it.
- types.ts: NodeDefinition, Capabilities, Relations, DragAction, Plugin,
ParametricDescriptor, Affordance, SceneApi, NodeRegistry. Capability
configs accept an override escape hatch; additive-only after v1.
- registry.ts: nodeRegistry singleton, registerNode, async loadPlugin.
Validates kind, schemaVersion, apiVersion; rejects duplicate kinds.
- scene-api.ts: createSceneApi factory wrapping the scene store with
copy-on-write snapshot semantics for pauseHistory/restore/resumeHistory.
- index.ts: barrel re-exporting the public surface.
- core/index.ts + package.json: export * from registry and add the
./registry subpath so consumers can import either way.
Tests (27 cases, all bun:test): registry registration / validation /
plugin loading; SceneApi read/write/dirty/history; lazy snapshot capture
with update/upsert/delete reversal via restore and restoreAll.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
