forked from 1b-agent/opencadstudio-upstream
Reference-only entities (plugin API v9): a scene-scoped, in-memory designation for plugin-owned display geometry, plus HostNotification dispatch to native plugins so they can re-mark on DocumentOpened. Resolves the new DeltaSnapshot site in block_editor.rs. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>