fix(export): snap levels to stacked positions before GLB export

exportSceneToGlb now calls snapLevelsToTruePositions() (the same clean stacked
presentation thumbnail capture uses) before snapshotting the scene, so the GLB
always reflects the stacked building regardless of the live levelMode
(exploded/solo) or an unsettled level lerp. Fixes baked GLBs where a level was
captured at a stray offset (e.g. ~ -100k Y), which inflated the bounding box and
made the model unframable / invisible in third-party glTF viewers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/editor/src/lib/glb-export.ts

@@ -7,7 +7,7 @@ import {
   type WindowNode,
   type ZoneNode,
 } from '@pascal-app/core'
-import { poseWindowMovingParts, SCENE_LAYER } from '@pascal-app/viewer'
+import { poseWindowMovingParts, SCENE_LAYER, snapLevelsToTruePositions } from '@pascal-app/viewer'
 import type { Object3D } from 'three'
 import * as THREE from 'three'
 import { GLTFExporter } from 'three/examples/jsm/exporters/GLTFExporter.js'
@@ -36,10 +36,16 @@ export async function exportSceneToGlb(
   nodes: Record<string, AnyNode>,
 ): Promise<ArrayBuffer> {
   emitter.emit('thumbnail:before-capture', undefined)
+  // Snap levels to their true stacked positions (like thumbnail capture) so the
+  // export always reflects the clean stacked building, regardless of the live
+  // levelMode (exploded/solo) or an unsettled level lerp that could otherwise
+  // bake a level at a stray offset.
+  const restoreLevels = snapLevelsToTruePositions()
   let prepared: ReturnType<typeof prepareSceneForExport>
   try {
     prepared = prepareSceneForExport(sceneGroup, nodes)
   } finally {
+    restoreLevels()
     emitter.emit('thumbnail:after-capture', undefined)
   }
   const { scene: exportScene, animations } = prepared