feat(paint-slots): authored item materials + unified slot painting

Phase 1 + paint unification of the paint-slots plan.

- core: scene-material data layer (materials map mirroring collections,
  undo/partialize/setScene full-graph support), SceneMaterial schema,
  scene:/library: MaterialRef helpers + parseMaterialRef, slot id helpers
  (deriveSlotId/slotLabelFromId), slots map on ItemNode, hitObject on
  PaintResolveArgs, optional PaintCapability.commit.
- viewer: resolveMaterialRef (library:/scene: -> three material, null on
  dangling).
- nodes(item): renderer keeps authored GLB materials for slot-authored
  assets and applies per-slot overrides per-instance (never mutates the
  shared cached GLB); textures-off still collapses to furnishing role;
  non-authored items unchanged. Item paint capability + registration.
- editor: item joins the unified (nodeId, slotId) paint dispatch; item
  paint target + slot reset.

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

packages/editor/src/components/editor/selection-manager.tsx

@@ -906,6 +906,7 @@ export const SelectionManager = () => {
           normal: event.normal,
           localPosition: event.localPosition as readonly [number, number, number] | undefined,
           hitObjectName: event.nativeEvent.object?.name,
+          hitObject: getEventObject(event),
         })
         const compatible = role !== null && paintEnabled
         return {
@@ -915,15 +916,22 @@ export const SelectionManager = () => {
           apply:
             compatible && role
               ? () => {
-                  useScene.getState().updateNode(
-                    node.id as AnyNodeId,
-                    paintCap.buildPatch({
-                      node,
-                      role,
-                      material: paintSpec.material,
-                      materialPreset: paintSpec.materialPreset,
-                    }) as Partial<AnyNode>,
-                  )
+                  const args = {
+                    node,
+                    role,
+                    material: paintSpec.material,
+                    materialPreset: paintSpec.materialPreset,
+                  }
+                  if (paintCap.commit) {
+                    paintCap.commit(args)
+                  } else {
+                    useScene
+                      .getState()
+                      .updateNode(
+                        node.id as AnyNodeId,
+                        paintCap.buildPatch(args) as Partial<AnyNode>,
+                      )
+                  }
                 }
               : null,
           preview:
@@ -1086,7 +1094,7 @@ export const SelectionManager = () => {
         }
       }
 
-      const disabledNodeTypes = ['item', 'window', 'door', 'zone']
+      const disabledNodeTypes = ['window', 'door', 'zone']
       if (disabledNodeTypes.includes(node.type)) {
         return {
           key: `${node.type}:${node.id}:unsupported`,
@@ -1549,6 +1557,7 @@ export const SelectionManager = () => {
               normal: event.normal,
               localPosition: event.localPosition as readonly [number, number, number] | undefined,
               hitObjectName: event.nativeEvent.object?.name,
+              hitObject: getEventObject(event),
             })
             if (role) {
               setSelectedMaterialTargetForNode(nodeToSelect, role as MaterialTargetRole)
@@ -1930,7 +1939,8 @@ const SelectionStateSync = () => {
     const selectedNode = useScene.getState().nodes[singleSelectedId as AnyNodeId]
     if (
       !selectedNode ||
-      (selectedNode.type !== 'wall' &&
+      (!nodeRegistry.get(selectedNode.type)?.capabilities?.paint &&
+        selectedNode.type !== 'wall' &&
         selectedNode.type !== 'fence' &&
         selectedNode.type !== 'slab' &&
         selectedNode.type !== 'ceiling' &&

packages/editor/src/lib/material-paint.ts

@@ -30,24 +30,26 @@ import {
   type WallSurfaceSide,
 } from '@pascal-app/core'
 
-export type PaintableMaterialTarget = Extract<
-  MaterialTarget,
-  | 'wall'
-  | 'roof'
-  | 'stair'
-  | 'fence'
-  | 'column'
-  | 'slab'
-  | 'ceiling'
-  | 'shelf'
-  | 'chimney'
-  | 'dormer'
-  | 'box-vent'
-  | 'ridge-vent'
-  | 'turbine-vent'
-  | 'cupola'
-  | 'eyebrow-vent'
->
+export type PaintableMaterialTarget =
+  | Extract<
+      MaterialTarget,
+      | 'wall'
+      | 'roof'
+      | 'stair'
+      | 'fence'
+      | 'column'
+      | 'slab'
+      | 'ceiling'
+      | 'shelf'
+      | 'chimney'
+      | 'dormer'
+      | 'box-vent'
+      | 'ridge-vent'
+      | 'turbine-vent'
+      | 'cupola'
+      | 'eyebrow-vent'
+    >
+  | 'item'
 
 export type SingleSurfaceMaterialRole = 'surface'
 
@@ -179,6 +181,7 @@ export function buildResetSurfaceMaterialUpdates(
       if (
         key === 'material' ||
         key === 'materialPreset' ||
+        key === 'slots' ||
         key.endsWith('Material') ||
         key.endsWith('MaterialPreset')
       ) {
@@ -276,6 +279,7 @@ export function resolveActivePaintMaterialFromSelection(params: {
       | ChimneyMaterialRole
       | DormerSurfaceMaterialRole
       | SingleSurfaceMaterialRole
+      | string
   } | null
 }): ActivePaintMaterial | null {
   const { nodes, selectedId, selectedMaterialTarget } = params
@@ -444,6 +448,10 @@ export function resolvePaintTargetFromSelection(params: {
     return 'shelf'
   }
 
+  if (selectedNode.type === 'item') {
+    return 'item'
+  }
+
   if (selectedNode.type === 'chimney') {
     return 'chimney'
   }

packages/editor/src/store/use-editor.tsx

@@ -168,6 +168,7 @@ export type MaterialTargetRole =
   | ChimneyMaterialRole
   | DormerSurfaceMaterialRole
   | SingleSurfaceMaterialRole
+  | string
 
 export type SelectedMaterialTarget = {
   nodeId: AnyNodeId