- Mode system: view | select | move | rotate | place
- Click furniture to select with cyan wireframe outline
- Keyboard: R/Shift+R rotate, Delete remove, Escape deselect,
Ctrl+Z undo, Ctrl+Shift+Z/Ctrl+Y redo
- Listens to DesignState changes to sync scene on undo/redo
- Wired into index.html with DesignState integration
- Added furnitureIndex to mesh userData for state lookups