fix(editor): harden editor interactions and WebGPU rendering

Fix editor bug sweep regressions, WebGPU CSG/material crashes, Shift snap bypass behavior, arrow handle drag projection, and the wall preview null guard covered by the Sentry follow-up PRs.

packages/nodes/src/ceiling/move-tool.tsx

@@ -147,10 +147,12 @@ export const MoveCeilingTool: React.FC<{ node: CeilingNode }> = ({ node }) => {
 
     const onGridMove = (event: GridEvent) => {
       if (isFloorplanSourcedEvent(event)) return
-      const localX = snap(event.localPosition[0])
-      const localZ = snap(event.localPosition[2])
+      const bypassSnap = event.nativeEvent?.shiftKey === true
+      const localX = bypassSnap ? event.localPosition[0] : snap(event.localPosition[0])
+      const localZ = bypassSnap ? event.localPosition[2] : snap(event.localPosition[2])
 
       if (
+        !bypassSnap &&
         previousGridPosRef.current &&
         (localX !== previousGridPosRef.current[0] || localZ !== previousGridPosRef.current[1])
       ) {
@@ -166,8 +168,8 @@ export const MoveCeilingTool: React.FC<{ node: CeilingNode }> = ({ node }) => {
 
       // Figma-style alignment snap: align the ceiling's translated polygon
       // vertices to other objects' anchors; fold the snap into the delta and
-      // publish a guide. Alt bypasses.
-      const bypass = event.nativeEvent?.altKey === true
+      // publish a guide. Alt bypasses alignment; Shift bypasses all snap.
+      const bypass = event.nativeEvent?.altKey === true || bypassSnap
       if (!bypass && alignmentCandidates.length > 0) {
         const result = resolveAlignment({
           moving: polygonAnchors(ceilingId, translatePolygon(originalPolygon, deltaX, deltaZ)),