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/door/door-math.ts

@@ -0,0 +1,110 @@
+import {
+  type AnyNodeId,
+  type DoorNode,
+  getScaledDimensions,
+  type ItemNode,
+  useScene,
+  type WallNode,
+  type WindowNode,
+} from '@pascal-app/core'
+
+/**
+ * Converts wall-local (X along wall, Y = height above wall base) to world XYZ.
+ */
+export function wallLocalToWorld(
+  wallNode: WallNode,
+  localX: number,
+  localY: number,
+  levelYOffset = 0,
+  slabElevation = 0,
+): [number, number, number] {
+  const wallAngle = Math.atan2(
+    wallNode.end[1] - wallNode.start[1],
+    wallNode.end[0] - wallNode.start[0],
+  )
+  return [
+    wallNode.start[0] + localX * Math.cos(wallAngle),
+    slabElevation + localY + levelYOffset,
+    wallNode.start[1] + localX * Math.sin(wallAngle),
+  ]
+}
+
+/**
+ * Clamps door center X so it stays fully within wall bounds.
+ * Y is always height/2 — doors sit at floor level.
+ */
+export function clampToWall(
+  wallNode: WallNode,
+  localX: number,
+  width: number,
+  height: number,
+): { clampedX: number; clampedY: number } {
+  const dx = wallNode.end[0] - wallNode.start[0]
+  const dz = wallNode.end[1] - wallNode.start[1]
+  const wallLength = Math.sqrt(dx * dx + dz * dz)
+
+  const clampedX = Math.max(width / 2, Math.min(wallLength - width / 2, localX))
+  const clampedY = height / 2 // Doors always sit at floor level
+  return { clampedX, clampedY }
+}
+
+/**
+ * Checks if a proposed door position overlaps any existing wall children.
+ * Handles item, window, and door types.
+ */
+export function hasWallChildOverlap(
+  wallId: string,
+  clampedX: number,
+  clampedY: number,
+  width: number,
+  height: number,
+  ignoreId?: string,
+): boolean {
+  const nodes = useScene.getState().nodes
+  const wallNode = nodes[wallId as AnyNodeId] as WallNode | undefined
+  if (!wallNode) return true
+  const halfW = width / 2
+  const halfH = height / 2
+  const newBottom = clampedY - halfH
+  const newTop = clampedY + halfH
+  const newLeft = clampedX - halfW
+  const newRight = clampedX + halfW
+
+  for (const childId of Array.isArray(wallNode.children) ? wallNode.children : []) {
+    if (childId === ignoreId) continue
+    const child = nodes[childId as AnyNodeId]
+    if (!child) continue
+
+    let childLeft: number, childRight: number, childBottom: number, childTop: number
+
+    if (child.type === 'item') {
+      const item = child as ItemNode
+      if (item.asset.attachTo !== 'wall' && item.asset.attachTo !== 'wall-side') continue
+      const [w, h] = getScaledDimensions(item)
+      childLeft = item.position[0] - w / 2
+      childRight = item.position[0] + w / 2
+      childBottom = item.position[1]
+      childTop = item.position[1] + h
+    } else if (child.type === 'window') {
+      const win = child as WindowNode
+      childLeft = win.position[0] - win.width / 2
+      childRight = win.position[0] + win.width / 2
+      childBottom = win.position[1] - win.height / 2
+      childTop = win.position[1] + win.height / 2
+    } else if (child.type === 'door') {
+      const door = child as DoorNode
+      childLeft = door.position[0] - door.width / 2
+      childRight = door.position[0] + door.width / 2
+      childBottom = door.position[1] - door.height / 2
+      childTop = door.position[1] + door.height / 2
+    } else {
+      continue
+    }
+
+    const xOverlap = newLeft < childRight && newRight > childLeft
+    const yOverlap = newBottom < childTop && newTop > childBottom
+    if (xOverlap && yOverlap) return true
+  }
+
+  return false
+}