Rewrite sync module to work with SceneManager and v2 scene format
instead of Fabric.js. Key changes:
- setupSync takes SceneManager instead of Canvas
- broadcastScene uses sceneManager.serialize() for v2 SceneData
- broadcastTransform reads from item.data (x,y,sx,sy,angle)
- onSceneReceived uses diff-based loadScene (no flicker, no full reload)
- onTransformReceived updates item.data + displayObject directly
- Remove _suppress/resumeBroadcasts (diff-based loading is safe)
- Remove userInteracting/pendingScene deferral (not needed with diffs)
- Remove all Fabric.js imports and types
Full-featured PureRef-style collaborative canvas for game dev teams:
- Layer panel with visibility, lock, drag reorder, group/ungroup (Ctrl+G/Shift+G)
- Arrangement tools (grid, row, column) via right-click context menu
- Copy to system clipboard (Ctrl+C writes PNG for external paste in Paint etc.)
- Number shortcuts (1-5) for tool selection with visible shortcut badges
- Premium dark UI across all pages (Login, Collections, Boards, Editor)
- Socket.IO rooms for cursors, transforms, and presence notifications
- MinIO image storage with backend proxy, drag/drop and paste upload
Hiren Kangad