Closes https://github.com/webstudio-is/webstudio/issues/4586
Closes https://github.com/webstudio-is/webstudio/issues/4619
## Summary
Fixes shared Slot editing so linked Slot occurrences stay consistent
across structural edits and labels.
## Changes
- Fixed moving a direct Slot child out of a Slot so the child is removed
from all linked Slot occurrences.
- Fixed unwrapping a direct Slot child so the child is removed from all
linked Slot occurrences.
- Added linked Slot label sync when renaming from Navigator or Settings
panel.
- Added/updated tests for canonical Slots, legacy Slots, nested Slot
children, keyboard moves, unwrap, reparent, and label sync.
- Simplified stale Slot detach logic that was incorrectly cloning only
the selected Slot occurrence.
## Testing
- `pnpm --filter @webstudio-is/builder test --
app/shared/instance-utils/...`
- `pnpm --filter @webstudio-is/builder test --
app/builder/shared/commands.test.ts`
- `pnpm --filter @webstudio-is/builder typecheck`
- `pnpm lint`
- `git diff --check`
Oleg Isonen