Phase 5 Stage E: full kind migration into packages/nodes

Wholesale move of every remaining kind into its own subdirectory under
`packages/nodes/src/`, finishing the registry-driven migration. Each
kind now ships its definition, schema (re-exported from core), and any
of `geometry` / `renderer` / `system` / `floorplan` / `tool` /
`move-tool` / `panel` / `floorplan-move` / `floorplan-affordances` /
`parametrics` / `preview` it needs — no per-kind code remains under
`packages/editor/src/components/tools/` or
`packages/viewer/src/components/renderers/`.

Deleted (replaced by registry-driven equivalents):
- `tools/{ceiling,column,door,fence,item,slab,spawn,wall,window}/...`
  (boundary editors, hole editors, placement tools, move tools,
  endpoint movers, curve tools, helpers, math libs)
- `ui/helpers/{ceiling,slab,wall}-helper.tsx`
- `ui/panels/{column,door,elevator,item,roof,roof-segment,spawn,
  stair,stair-segment,wall,window}-panel.tsx`
- `viewer/src/components/renderers/{building,ceiling,column,door,
  elevator,fence,guide,item,level,roof,roof-segment,scan,site,slab,
  spawn,stair,stair-segment,wall,window,zone}-renderer.tsx`
- `viewer/src/components/viewer/legacy-system.tsx`

Added under `packages/nodes/src/`:
- `building/`, `column/`, `elevator/`, `guide/`, `level/`, `roof/`,
  `roof-segment/`, `scan/`, `shared/`, `site/`, `stair/`,
  `stair-segment/` packages with definition + schema + renderer / system
  / floorplan / panel as appropriate.
- New `floorplan-move.ts` for every kind that supports 2D moves
  (ceiling, door, item, shelf, slab, window) — single registry-driven
  dispatch path via `def.floorplanMoveTarget`.
- New `floorplan-affordances.ts` for kinds with polygon / endpoint
  drags (ceiling, fence, slab, wall) — using the shared
  `polygon-vertex-affordance` factories.
- New per-kind `panel.tsx` for kinds with custom inspector content
  (door, item, shelf, spawn, wall, window).
- New per-kind `tool.tsx` for placement (door, item, shelf, window).
- New per-kind `move-tool.tsx` for kinds with custom 3D move flows
  (door, item, slab, window).

Coordinator + manager updates in `packages/editor/`:
- `tool-manager.tsx` resolves tools from the registry only — no
  hardcoded type→component map.
- `panel-manager.tsx` resolves inspector panels the same way.
- `placement-{coordinator,strategies,types}.ts` extended with
  shelf-surface placement.
- `selection-manager.tsx` adds the registry-selectable fallback.
- `floorplan-panel.tsx`, `floorplan-background-placement.ts`,
  `floorplan-render-context.tsx` updated for the registry layer's new
  contract (props, affordance dispatch, render context).

Viewer updates:
- `viewer/index.tsx` drops legacy renderer mounts.
- `node-renderer.tsx` resolves by registry only.
- `scene-bvh.tsx`, `use-node-events.ts`, `level-system.tsx`,
  `wall-cutout.tsx`, `zone-system.tsx`, `materials.ts` adjusted for
  the registry-only world.

Sidebar tree nodes for ceiling / fence / slab / shelf / tree-node
updated to read from the registered nodes instead of the deleted
legacy renderer trees.

Wiki: new `plugin-authoring.md` page, README index updated.

Tests in `packages/nodes/src/index.test.ts` validate every registered
kind has the required shape.

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

packages/nodes/src/ceiling/renderer.tsx

@@ -1,15 +1,106 @@
 'use client'
 
-import { CeilingRenderer } from '@pascal-app/viewer'
+import {
+  type CeilingNode,
+  getMaterialPresetByRef,
+  resolveMaterial,
+  useRegistry,
+} from '@pascal-app/core'
+import { NodeRenderer, useNodeEvents } from '@pascal-app/viewer'
+import { useEffect, useMemo, useRef } from 'react'
+import { BufferGeometry, Float32BufferAttribute } from 'three'
+import { float, mix, positionWorld, smoothstep } from 'three/tsl'
+import { BackSide, FrontSide, type Mesh, MeshBasicNodeMaterial } from 'three/webgpu'
+
+function createEmptyGeometry() {
+  const geometry = new BufferGeometry()
+  geometry.setAttribute('position', new Float32BufferAttribute([], 3))
+  return geometry
+}
+
+const gridScale = 5
+const gridX = positionWorld.x.mul(gridScale).fract()
+const gridY = positionWorld.z.mul(gridScale).fract()
+const lineWidth = 0.05
+const lineX = smoothstep(lineWidth, 0, gridX).add(smoothstep(1.0 - lineWidth, 1.0, gridX))
+const lineY = smoothstep(lineWidth, 0, gridY).add(smoothstep(1.0 - lineWidth, 1.0, gridY))
+const gridPattern = lineX.max(lineY)
+const gridOpacity = mix(float(0.2), float(0.6), gridPattern)
+
+function createCeilingMaterials(color = '#999999') {
+  const topMaterial = new MeshBasicNodeMaterial({
+    color,
+    transparent: true,
+    depthWrite: false,
+    side: FrontSide,
+  })
+  topMaterial.opacityNode = gridOpacity
+
+  const bottomMaterial = new MeshBasicNodeMaterial({
+    color,
+    transparent: true,
+    side: BackSide,
+  })
+
+  return { topMaterial, bottomMaterial }
+}
+
+const ceilingMaterialCache = new Map<string, ReturnType<typeof createCeilingMaterials>>()
+
+function getCeilingMaterials(color = '#999999') {
+  const cacheKey = color
+  const cached = ceilingMaterialCache.get(cacheKey)
+  if (cached) return cached
+
+  const materials = createCeilingMaterials(color)
+  ceilingMaterialCache.set(cacheKey, materials)
+  return materials
+}
+
+export const CeilingRenderer = ({ node }: { node: CeilingNode }) => {
+  const ref = useRef<Mesh>(null!)
+  const placeholderGeometry = useMemo(createEmptyGeometry, [])
+  const gridPlaceholderGeometry = useMemo(createEmptyGeometry, [])
+
+  useRegistry(node.id, 'ceiling', ref)
+  const handlers = useNodeEvents(node, 'ceiling')
+
+  useEffect(
+    () => () => {
+      placeholderGeometry.dispose()
+      gridPlaceholderGeometry.dispose()
+    },
+    [gridPlaceholderGeometry, placeholderGeometry],
+  )
+
+  const materials = useMemo(() => {
+    const preset = getMaterialPresetByRef(node.materialPreset)
+    const props = preset?.mapProperties ?? resolveMaterial(node.material)
+    const color = props.color || '#999999'
+    return getCeilingMaterials(color)
+  }, [
+    node.materialPreset,
+    node.material,
+    node.material?.preset,
+    node.material?.properties,
+    node.material?.texture,
+  ])
+
+  return (
+    <mesh geometry={placeholderGeometry} material={materials.bottomMaterial} ref={ref}>
+      <mesh
+        geometry={gridPlaceholderGeometry}
+        material={materials.topMaterial}
+        name="ceiling-grid"
+        {...handlers}
+        scale={0}
+        visible={false}
+      />
+      {node.children.map((childId) => (
+        <NodeRenderer key={childId} nodeId={childId} />
+      ))}
+    </mesh>
+  )
+}
 
-/**
- * Wrap-export of the legacy `CeilingRenderer`.
- *
- * Ceiling's renderer uses TSL shader code for the grid-line pattern
- * (~100 lines incl. material setup) — too much to duplicate at Stage A.
- * The legacy file stays in viewer; the registry imports it through the
- * public export. Phase 5 Stage B/F (per-kind migration stages, see
- * plans/editor-node-registry.md) moves the renderer body into this
- * folder and deletes the legacy file.
- */
 export default CeilingRenderer