POC for cross-app embedding (TASK-46). New folk-rapp shape type that
embeds any rApp module as a live iframe inside a canvas shape. Features:
- Module picker dropdown when no module selected
- Colored header with module badge/icon
- Open-in-tab action button
- Syncs moduleId + spaceSlug via Automerge CRDT
- Toolbar rApps section now creates folk-rapp (not generic folk-embed)
- Fixed stale "canvas" moduleId refs → "rspace" in canvas.html
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
