Phase 5 batch kind: item migrates to registry (always-on)

Item is the first kind to use the `def.renderer` escape hatch (custom
React component with `useGLTF` + drei + interactive widgets) — not
expressible as a pure `def.geometry`. Catalog-backed + multi-host
(free / wall / wall-side / ceiling).

Files added (packages/nodes/src/item/):
 - schema.ts: re-exports ItemNode from core.
 - parametrics.ts: empty groups[]. Item parametrics come from the
   asset's catalog-defined interactive controls (toggles / sliders /
   temperature) — too dynamic for the auto-inspector at Stage A.
   Legacy ItemPanel renders the catalog-driven controls; Phase 5
   Stage E will likely use parametrics.customPanel.
 - definition.ts: capabilities (no `movable` — item move is bespoke
   MoveItemContent that handles attachTo transitions floor↔wall↔
   ceiling mid-drag; capability-driven dispatch keeps legacy mover),
   parametrics, renderer (wrap-export of ItemRenderer), system
   bundling ItemSystem + ItemLightSystem, toolHints matching the
   user's screenshot (Place item / R rotate ccw / T rotate cw /
   Shift free place / Esc cancel). defaults() casts an object
   literal with a stub asset since asset is required by the schema;
   createNode re-parses through ItemNode at runtime.
 - renderer.tsx: wrap-export of legacy ItemRenderer (~280 lines with
   useGLTF + interactive widgets — too much to duplicate at Stage A).
 - system.tsx: bundles ItemSystem + ItemLightSystem.
 - index.ts: barrel.

Files changed:
 - packages/viewer/src/index.ts: new public exports for ItemRenderer,
   ItemSystem, ItemLightSystem.
 - packages/nodes/src/index.ts: appends itemDefinition.
 - packages/editor/src/components/ui/panels/item-panel.tsx: panel
   slider-drag fix recipe applied (nodeRef pattern, drop subscribed
   updateNode dep, drop node from useCallback deps). Item panel has
   scale + position + rotation sliders all subject to the cascade.

Item is the registry's stress test for `def.renderer` escape hatch.
GLB loading via useGLTF + drei works as-is; nothing in the registry
forces a pure-geometry shape on kinds that don't fit.

Phase 5 progress: shelf ✅ spawn ✅ wall ✅ fence ✅ slab ✅ ceiling ✅
door ✅ window ✅ item ✅. Nine kinds on the registry. Stair / roof /
zone / containers remain.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/editor/src/components/ui/panels/item-panel.tsx

@@ -3,7 +3,7 @@
 import { type AnyNode, getScaledDimensions, ItemNode, useScene } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
 import { Copy, Link, Link2Off, Move, Trash2 } from 'lucide-react'
-import { useCallback, useState } from 'react'
+import { useCallback, useRef, useState } from 'react'
 import { sfxEmitter } from '../../../lib/sfx-bus'
 import { cn } from '../../../lib/utils'
 import useEditor from '../../../store/use-editor'
@@ -16,7 +16,6 @@ import { PanelWrapper } from './panel-wrapper'
 export function ItemPanel() {
   const selectedId = useViewer((s) => s.selection.selectedIds[0])
   const setSelection = useViewer((s) => s.setSelection)
-  const updateNode = useScene((s) => s.updateNode)
   const deleteNode = useScene((s) => s.deleteNode)
   const setMovingNode = useEditor((s) => s.setMovingNode)
 
@@ -26,18 +25,26 @@ export function ItemPanel() {
 
   const [uniformScale, setUniformScale] = useState(true)
 
+  // Panel slider-drag fix recipe (plans/editor-node-registry.md). Item
+  // panel has scale + position + rotation sliders — same Maximum update
+  // depth cascade risk as fence / wall / etc. without the nodeRef.
+  const nodeRef = useRef(node)
+  nodeRef.current = node
+
   const handleUpdate = useCallback(
     (updates: Partial<ItemNode>) => {
-      if (!(selectedId && node)) return
-      updateNode(selectedId as AnyNode['id'], updates)
+      if (!selectedId) return
+      const n = nodeRef.current
+      if (!n) return
+      useScene.getState().updateNode(selectedId as AnyNode['id'], updates)
 
-      if (node.asset.attachTo === 'wall' && node.parentId) {
+      if (n.asset.attachTo === 'wall' && n.parentId) {
         requestAnimationFrame(() => {
-          useScene.getState().dirtyNodes.add(node.parentId as AnyNode['id'])
+          useScene.getState().dirtyNodes.add(n.parentId as AnyNode['id'])
         })
       }
     },
-    [selectedId, node, updateNode],
+    [selectedId],
   )
 
   const handleClose = useCallback(() => {