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/nodes/src/item/definition.ts

@@ -0,0 +1,110 @@
+import type { ItemNode as ItemNodeType, NodeDefinition } from '@pascal-app/core'
+import { itemParametrics } from './parametrics'
+import { ItemNode } from './schema'
+
+/**
+ * Item — Phase 5 batch kind. Catalog-backed, GLB-rendered, multi-host.
+ *
+ * Demonstrates the **custom `def.renderer` escape hatch** (see
+ * plans/editor-node-registry.md): items use `useGLTF` from drei to
+ * load CDN assets, plus a non-trivial interactive-widget layer inside
+ * the rendered scene. Not expressible as a pure `def.geometry`. The
+ * registry mounts the custom React renderer as-is.
+ *
+ * Capabilities:
+ *  - **No `movable`**: item's move is bespoke `MoveItemContent` —
+ *    handles attachTo transitions mid-drag (floor ↔ wall ↔ ceiling),
+ *    asset.attachTo lookups, scale-preserving Y math for surface
+ *    placement. The smooth generic mover can't express that. Legacy
+ *    mover keeps running via capability-driven dispatch.
+ *  - `selectable`, `duplicable`, `deletable` standard.
+ *  - Items have a catalog-defined `surface.height` (some items act as
+ *    tables — they expose a surface other items stack on). For Stage A
+ *    we don't surface this via `capabilities.surfaces.top` yet —
+ *    legacy ItemSystem computes the stack y via spatial-grid lookups.
+ *    Phase 5+ may surface it.
+ *
+ * `toolHints`: matches the legacy ItemHelper UI (mouse / R / T / Shift /
+ * Esc) — same panel the user sees during placement. Once item registers,
+ * `HelperManager` consults `def.toolHints` and renders the
+ * `RegisteredToolHelper` for placement (the legacy ItemHelper still
+ * renders for movingNode state — that's a generic "you're moving
+ * something" panel, not item-specific; Phase 5+ may deprecate it).
+ *
+ * Renderer + system: wrap-export of legacy ItemRenderer + bundle of
+ * ItemSystem + ItemLightSystem.
+ *
+ * Tool field absent: catalog UI + item-tool placement flow stays on
+ * editor state. Phase 5+ may port to `DragAction` once the registry's
+ * catalog-aware affordances exist.
+ */
+export const itemDefinition: NodeDefinition<typeof ItemNode> = {
+  kind: 'item',
+  schemaVersion: 1,
+  schema: ItemNode,
+  category: 'furnish',
+
+  // Defaults shape is cast: the schema requires a fully-typed `asset`
+  // field, but in practice items are always created from the catalog
+  // (the asset is supplied at placement time). `createNode` re-parses
+  // through the schema, so any missing zod defaults fill at runtime.
+  defaults: () =>
+    ({
+      object: 'node',
+      parentId: null,
+      visible: true,
+      metadata: {},
+      children: [],
+      position: [0, 0, 0],
+      rotation: [0, 0, 0],
+      scale: [1, 1, 1],
+      asset: {
+        id: 'placeholder',
+        category: 'misc',
+        name: 'Item',
+        thumbnail: '',
+        src: 'asset:placeholder',
+        dimensions: [1, 1, 1],
+        source: 'library',
+      },
+    }) as unknown as Omit<ItemNodeType, 'id' | 'type'>,
+
+  capabilities: {
+    selectable: { hitVolume: 'bbox' },
+    duplicable: true,
+    deletable: true,
+  },
+
+  parametrics: itemParametrics,
+
+  renderer: {
+    kind: 'parametric',
+    module: () => import('./renderer'),
+  },
+  system: {
+    module: () => import('./system'),
+    // Same priority as the legacy ItemSystem.
+    priority: 2,
+  },
+
+  toolHints: [
+    { key: 'Left click', label: 'Place item' },
+    { key: 'R', label: 'Rotate counterclockwise' },
+    { key: 'T', label: 'Rotate clockwise' },
+    { key: 'Shift', label: 'Free place' },
+    { key: 'Esc', label: 'Cancel' },
+  ],
+
+  presentation: {
+    label: 'Item',
+    description: 'A catalog-backed item (furniture, fixtures, decorations).',
+    icon: { kind: 'iconify', name: 'lucide:armchair' },
+    paletteSection: 'furnish',
+    paletteOrder: 10,
+  },
+
+  mcp: {
+    description:
+      'A catalog-backed item with asset reference, transforms, and optional attachTo for wall/ceiling mounting.',
+  },
+}