refactor: release-review cleanup for roof wall openings

Dual review pass (Claude multi-angle + Codex release-quality). One
correctness fix and the agreed do-now cleanups:

- fix: clone-scene-graph remaps roofSegmentId like wallId in both
  clone paths — duplicated scenes/levels kept pointing roof-hosted
  children at the original segments.
- extract the settled, stateless roof target/cursor math shared by the
  four door/window tools into shared/roof-wall-opening-placement.ts
  (resolveRoofWallOpeningTarget + getRoofWallOpeningCursorPose +
  worldToSelectedBuildingLocal); tools keep the stateful lifecycle
  (drafts, undo/temporal, commit field lists). −199 net lines.
- rename host-generic state: currentWallId→currentHostId,
  markWallDirty→markHostDirty (they hold segment ids too); capability
  cascadesViaHostSegment→dirtyHandledByOwnSystem (behavior-facing,
  before the public API hardens).
- drop getRoofAccessoryKinds from core's public API — its only caller
  was the standalone Build tab, which now enumerates the registry
  inline with its app-specific filter.
- window move-tool uses the shared stripPlacementMetadataFlags; stale
  "segment-local" comment fixed.

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

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

@@ -110,12 +110,12 @@ export const RoofSystem = () => {
       // previous cut shape (stale CSG) once the user exits segment
       // edit mode. Registry-driven so the viewer stays kind-agnostic.
       const def = nodeRegistry.get(node.type)
-      // Kinds with `cascadesViaHostSegment` (door / window) reach the roof
+      // Kinds with `dirtyHandledByOwnSystem` (door / window) reach the roof
       // through their own geometry system's parentId cascade instead —
       // their dirty marks belong to that system, not to this loop.
       if (
         def?.capabilities?.roofAccessory &&
-        !def.capabilities.roofAccessory.cascadesViaHostSegment
+        !def.capabilities.roofAccessory.dirtyHandledByOwnSystem
       ) {
         const segId = (node as { roofSegmentId?: string }).roofSegmentId
         const seg = segId ? (nodes[segId as AnyNodeId] as RoofSegmentNode | undefined) : undefined