Cascade of D20 (decisions/D20-id-type-convergence.md) from foundation:
- Rebuild packages/extension-api/build/index.d.ts via vite build so the
published .d.ts ships the new id/equals surface and drops the three
demoted brand re-exports.
- src/types/extensionV2.ts: stop re-exporting NodeEntityId, WidgetEntityId,
SlotEntityId — they are no longer in the @/extension-api barrel per D20.
Use node.id/widget.id (string) and equals(other) for the public surface.