PageScene: route viewport pointerup through sceneManager

useViewportPointer.onPointerUp called editor.mouse_controls.onMouseUp
directly. That ran the interaction state machine (gizmo end, FK toggle,
selection click) but skipped editor.sceneManager.onMouseUp, which is
the only thing that calls check_scene_for_updates. Result: transform,
deletion, and userdata edits (color, lock, visibility) never made it
into the undo stack, so Ctrl+Z found nothing to undo.

Pre-refactor, SceneManager.attachEventListeners attached a window-level
mouseup that went through SceneManager.onMouseUp; the canvas-scoped
hook lost the same pass-through. Calling sceneManager.onMouseUp here
preserves all the mouse_controls behavior (it forwards internally) and
restores the post-mouseup undo capture.

frontend/apps/artcraft/app/src/pages/PageScene/hooks/useViewportPointer.ts

@@ -43,7 +43,10 @@ export const useViewportPointer = (
     };
 
     const onPointerUp = (e: PointerEvent) => {
-      editor.mouse_controls?.onMouseUp(e);
+      // Route through sceneManager so check_scene_for_updates fires and
+      // transforms / deletions / userdata edits get pushed onto the undo
+      // stack. mouse_controls.onMouseUp is invoked from inside.
+      editor.sceneManager?.onMouseUp(e as unknown as MouseEvent);
     };
 
     const onClick = (_e: MouseEvent) => {