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/item/definition.ts

@@ -22,10 +22,10 @@ const ROTATE_RING_OFFSET = 0.06
 // Whole-item rotation handle — the two-headed curved arrow. `arc-resize`
 // does the angular drag math (raycasts a horizontal plane at the gizmo's
 // Y, measures cursor bearing around the item's local origin, returns the
-// delta). Holding Shift snaps to 15° increments (handled generically in
-// node-arrow-handles for any `shape: 'rotate'`), matching the R/T rotate
-// step for placed items. Item rotation is stored as `[x, y, z]`; only the
-// Y component turns.
+// delta). Rotation snaps to 15° increments by default; holding Shift
+// bypasses that snap (handled generically in node-arrow-handles for any
+// `shape: 'rotate'`), matching the R/T rotate step for placed items. Item
+// rotation is stored as `[x, y, z]`; only the Y component turns.
 function itemRotateHandle(): HandleDescriptor<ItemNodeType> {
   return {
     kind: 'arc-resize',