fix(editor): door/window move — fix 2D+3D FPS collapse + finish modifier migration

The 3D MoveDoor/MoveWindow tools wrote useScene every frame during a move
(freeFollowAt + applyPreview alternating): the wall:move (R3F) / grid:move
(DOM) de-dup compared event.timeStamp across two event systems with different
clocks, so it never matched and the floor free-follow ran during on-wall
slides too, ping-ponging the host and churning the nodes ref → framerate
collapse in both 2D and 3D. Replace it with a single-clock wall-ownership
window (performance.now, ~4 frames): the floor follow stands down while a
wall/roof hit is fresh. On-wall slides now write no scene per frame (mesh +
useLiveTransforms only). Lower the live wall-cutout throttle 120→60ms now that
the per-frame churn is gone.

Also completes the door/window modifier-model migration (#10): Shift=cycle /
Alt=force-place, fully mode-driven snap, snapProfile:'item'; exclude
ground-line candidates from along-wall opening alignment; emit the move SFX
once per snapped step.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/nodes/src/window/definition.ts

@@ -160,6 +160,7 @@ const windowHandles: HandleDescriptor<WindowNodeType>[] = [
  */
 export const windowDefinition: NodeDefinition<typeof WindowNode> = {
   kind: 'window',
+  snapProfile: 'item',
   schemaVersion: 1,
   schema: WindowNode,
   category: 'structure',
@@ -229,6 +230,8 @@ export const windowDefinition: NodeDefinition<typeof WindowNode> = {
 
   toolHints: [
     { key: 'Left click', label: 'Place window on wall' },
+    { key: 'R', label: 'Flip side' },
+    { key: 'Alt', label: 'Force place' },
     { key: 'Esc', label: 'Cancel' },
   ],