feat: face-frame hosting for roof wall children + items on roof walls

Wall-mounted items join doors/windows on roof-segment wall faces, and
the storage model moves to FACE-LOCAL coordinates so hosted children
track segment edits live.

- Children store roofFace + position [u, v, z-from-mid-plane] with
  rotation 0 in-frame — the exact wall-child conventions (the wall
  volume's mid-plane lands on the nominal footprint). A shared
  <RoofFaceHostFrame> derives segment pose + face frame from the
  live-override-merged segment: children follow resize handle drags in
  real time and never jump on commit. No re-anchor cascade needed —
  position is authoritative, the frame is derived. migrateNodes
  converts branch-era segment-local data.
- Items: roofWallStrategy + roof:* handlers in the placement
  coordinator (surface 'roof-wall'), Shift free-place normalized with
  walls, ItemSystem wall-side push extended to segment hosts, correct
  2D plan glyphs via face→segment→roof pose composition. The roof
  hit resolver + overlap guard moved to @pascal-app/editor (the
  coordinator lives there; nodes already depends on editor).
- Cuts: subtractAccessoryCuts extracted and applied in BOTH the
  merged-shell and per-segment CSG paths (full edit mode / painted
  segments used to lose every hole), built from the CURRENT host
  geometry and live-effective children so holes follow segment and
  opening drags.
- Handle rig: the grandparent portal now maps the node's world pose
  into the portal frame instead of composing parent+node registry
  poses — correct for any nesting (the face-frame group broke the
  old assumption), identical for walls.
- Host-field hygiene: useDraftNode.commit/adopt and the window panel
  duplicate forward roofSegmentId/roofFace/wallId; every roof↔wall
  re-anchor clears and every revert restores them.

Codex-reviewed (design consultation, adversarial rounds on the
replaced cascade and on this refactor); frame conventions locked by
unit tests. Record: private-editor plans/editor-roof-wall-openings.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/viewer/src/systems/item/item-system.tsx

@@ -36,12 +36,20 @@ export const ItemSystem = () => {
       if (!mesh) return
 
       if (item.asset.attachTo === 'wall-side') {
-        // Wall-attached item: offset Z by half the parent wall's thickness
-        const parentWall = item.parentId ? nodes[item.parentId as AnyNodeId] : undefined
-        if (parentWall && parentWall.type === 'wall') {
-          const wallThickness = (parentWall as WallNode).thickness ?? 0.1
+        // Wall-attached item: offset Z by half the host wall's thickness.
+        // Roof-segment wall faces share the convention — the face frame's
+        // z = 0 is the wall mid-plane, so the same push lands the item on
+        // the outer surface.
+        const parent = item.parentId ? nodes[item.parentId as AnyNodeId] : undefined
+        const thickness =
+          parent?.type === 'wall'
+            ? ((parent as WallNode).thickness ?? 0.1)
+            : parent?.type === 'roof-segment'
+              ? (parent.wallThickness ?? 0.1)
+              : undefined
+        if (thickness !== undefined) {
           const side = item.side === 'front' ? 1 : -1
-          mesh.position.z = (wallThickness / 2) * side
+          mesh.position.z = (thickness / 2) * side
         }
       }