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/nodes/src/window/definition.ts

@@ -152,12 +152,12 @@ export const windowDefinition: NodeDefinition<typeof WindowNode> = {
     wallOpeningPlacement: true,
     // Windows also host on roof-segment wall faces (base walls under the
     // roof, gable ends) — same wiring as door; see the door capability
-    // for why `cascadesViaHostSegment` is required.
+    // for why `dirtyHandledByOwnSystem` is required.
     roofAccessory: {
       buildCut: (node, hostSegment) =>
         buildRoofWallOpeningCut(node as WindowNodeType, hostSegment as RoofSegmentNode),
       cutScope: 'wall',
-      cascadesViaHostSegment: true,
+      dirtyHandledByOwnSystem: true,
     },
     // `wallId` / `roofSegmentId` are re-derived from the surface under
     // the cursor at preset placement time — see door for the pattern.