Phase 5 Stage D slab: port placement + move + boundary/hole editors

Replicates the fence Stage D recipe for slab — three drag affordances
+ one placement tool, all routed through the registry:

  affordanceTools:
    'boundary-edit' → thin <PolygonEditor> wrapper (vertex/edge drag)
    'hole-edit'     → same for a single hole polygon
    move            → DragAction with single-undo dance
  tool: () => placement (multi-click polygon with axis/45° snap)

`PolygonEditor` + `PolygonEditorProps` exported from
`@pascal-app/editor` as Stage D transitional surface (Stage F cleanup
moves them into `@pascal-app/nodes`).

ToolManager mount sites for SlabBoundaryEditor / SlabHoleEditor now
route through `getRegistryAffordanceTool` with legacy fallback.

Slab move action does not use the live-drag exception (polygon CSG
rebuild every tick) — matches legacy behavior; optimization is a
separate task once we measure.

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

packages/nodes/src/slab/move-tool.tsx

@@ -0,0 +1,66 @@
+'use client'
+
+import { type SlabNode, useScene } from '@pascal-app/core'
+import { CursorSphere, triggerSFX, useDragAction, useEditor } from '@pascal-app/editor'
+import { useViewer } from '@pascal-app/viewer'
+import { moveSlabDragAction } from './actions/move'
+
+/**
+ * Phase 5 Stage D — thin React wrapper around `moveSlabDragAction`.
+ *
+ * Replaces the legacy `MoveSlabTool` (182 LoC). All math + history
+ * dance lives in the action; this wrapper just renders the cursor
+ * sphere following the live polygon center.
+ */
+export const SlabMoveTool: React.FC<{ node: SlabNode }> = ({ node }) => {
+  const slabId = node.id
+
+  const initialCenter: [number, number] =
+    node.polygon.length > 0
+      ? [
+          node.polygon.reduce((s, [x]) => s + x, 0) / node.polygon.length,
+          node.polygon.reduce((s, [, z]) => s + z, 0) / node.polygon.length,
+        ]
+      : [0, 0]
+
+  // Live polygon center — re-derived from the scene store every tick
+  // since the action writes the translated polygon onto the slab.
+  const liveCenter = useScene((s) => {
+    const live = s.nodes[slabId]
+    if (live?.type !== 'slab') return initialCenter
+    const poly = (live as SlabNode).polygon
+    if (poly.length === 0) return initialCenter
+    let sx = 0
+    let sz = 0
+    for (const [x, z] of poly) {
+      sx += x
+      sz += z
+    }
+    return [sx / poly.length, sz / poly.length] as [number, number]
+  })
+
+  const exitMoveMode = (committed: boolean) => {
+    if (committed) triggerSFX('sfx:item-place')
+    useViewer.getState().setSelection({ selectedIds: [slabId] })
+    useEditor.getState().setMovingNode(null)
+  }
+
+  useDragAction({
+    active: true,
+    action: moveSlabDragAction,
+    initial: {
+      node,
+      point: initialCenter,
+    },
+    onCommit: () => exitMoveMode(true),
+    onCancel: () => exitMoveMode(false),
+  })
+
+  return (
+    <group>
+      <CursorSphere position={[liveCenter[0], 0, liveCenter[1]]} showTooltip={false} />
+    </group>
+  )
+}
+
+export default SlabMoveTool