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/gutter/geometry.ts

@@ -225,6 +225,7 @@ export function buildGutterGeometry(
       const drillBrush = new Brush(drill)
       prepareBrushForCSG(drillBrush)
       const next = csgEvaluator.evaluate(workingBrush, drillBrush, SUBTRACTION) as Brush
+      prepareBrushForCSG(next)
       // Free the previous step's intermediate result (but not `merged`,
       // which is disposed once below).
       if (workingBrush.geometry !== merged) workingBrush.geometry.dispose()

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

@@ -97,7 +97,10 @@ export default function MoveGutterTool({ node }: { node: GutterNode }) {
 
       const sx = Math.round(snap.eaveX * 20) / 20
       const sz = Math.round(snap.eaveZ * 20) / 20
-      if (!lastSnap || lastSnap[0] !== sx || lastSnap[1] !== sz) {
+      if (
+        event.nativeEvent?.shiftKey !== true &&
+        (!lastSnap || lastSnap[0] !== sx || lastSnap[1] !== sz)
+      ) {
         triggerSFX('sfx:grid-snap')
         lastSnap = [sx, sz]
       }

packages/nodes/src/gutter/tool.tsx

@@ -83,7 +83,7 @@ const GutterTool = () => {
       const sx = Math.round(snap.eaveX * 20) / 20
       const sz = Math.round(snap.eaveZ * 20) / 20
       const prev = lastSnapRef.current
-      if (!prev || prev[0] !== sx || prev[1] !== sz) {
+      if (event.nativeEvent?.shiftKey !== true && (!prev || prev[0] !== sx || prev[1] !== sz)) {
         triggerSFX('sfx:grid-snap')
         lastSnapRef.current = [sx, sz]
       }