Unify material target selection across wall stair and roof

packages/core/src/events/bus.ts

@@ -1,4 +1,5 @@
 import type { ThreeEvent } from '@react-three/fiber'
+import type { Object3D } from 'three'
 import mitt from 'mitt'
 import type {
   BuildingNode,
@@ -39,7 +40,7 @@ export interface NodeEvent<T extends AnyNode = AnyNode> {
   localPosition: [number, number, number]
   normal?: [number, number, number]
   faceIndex?: number
-  materialIndex?: number
+  object: Object3D
   stopPropagation: () => void
   nativeEvent: ThreeEvent<PointerEvent>
 }