Phase 5 Stage D fence: port MoveFenceTool to DragAction (whole-fence move)

Third Stage D affordance port (302 LoC legacy → action + thin wrapper).

The action (`actions/move.ts`) uses the live-drag exception documented
in editor/wiki/architecture/tools.md: visual-only updates via
`sceneRegistry.nodes.get(id).position` + `useLiveTransforms` during
the drag, no scene mutations. Avoids re-rebuilding the fence geometry
(many posts + infill panels) every pointer tick. Commit performs the
single-undo dance — writes final start/end to scene, geometry rebuilds
once, Ctrl-Z reverses the whole drag.

Linked-fence cascade follows the same shape as MoveFenceEndpoint —
any fence in the same parent that shared an endpoint at activation
moves with the drag.

`getRegistryAffordanceTool` extracted to
`tools/shared/affordance-dispatch.ts` so move-tool.tsx and
tool-manager.tsx share the lazy-load helper (no duplicate caches).

MoveTool dispatch gains a generic `affordanceTools.move` check after
the capability-driven `movable` shortcut — fence routes through here;
wall / slab / etc. fall through to their legacy per-kind chain until
their D ports land.

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

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

@@ -0,0 +1,61 @@
+'use client'
+
+import { type FenceNode, useLiveTransforms } from '@pascal-app/core'
+import { CursorSphere, triggerSFX, useDragAction, useEditor } from '@pascal-app/editor'
+import { useViewer } from '@pascal-app/viewer'
+import { moveFenceDragAction } from './actions/move'
+
+/**
+ * Phase 5 Stage D — thin React wrapper around `moveFenceDragAction`.
+ *
+ * Replaces the legacy `MoveFenceTool` (302 LoC). The action owns all
+ * the math (snap + linked cascade + live-drag mesh offsets +
+ * single-undo dance on commit). The wrapper just renders the cursor
+ * sphere and tracks its position from the live-transform store.
+ *
+ * Mounted by ToolManager when `useEditor.movingNode` is a fence
+ * (capability-driven dispatch — fence has no `movable` capability, so
+ * the legacy MoveTool's per-kind branch chain falls through to here
+ * via the new affordance dispatch).
+ */
+export const FenceMoveTool: React.FC<{ node: FenceNode }> = ({ node }) => {
+  const fenceId = node.id
+  const originalCenter: [number, number, number] = [
+    (node.start[0] + node.end[0]) / 2,
+    0,
+    (node.start[1] + node.end[1]) / 2,
+  ]
+
+  // Live position from the live-transforms store — the action writes
+  // here every preview tick (live-drag exception). Falls back to the
+  // original center until the first move.
+  const liveCenter = useLiveTransforms((s) => {
+    const t = s.get(fenceId)
+    return t?.position ?? originalCenter
+  })
+
+  const exitMoveMode = (committed: boolean) => {
+    if (committed) triggerSFX('sfx:item-place')
+    useViewer.getState().setSelection({ selectedIds: [fenceId] })
+    useEditor.getState().setMovingNode(null)
+  }
+
+  useDragAction({
+    active: true,
+    action: moveFenceDragAction,
+    initial: {
+      node,
+      point: [originalCenter[0], originalCenter[2]],
+    },
+    onCommit: () => exitMoveMode(true),
+    onCancel: () => exitMoveMode(false),
+  })
+
+  return (
+    <group>
+      <CursorSphere position={liveCenter as [number, number, number]} showTooltip={false} />
+    </group>
+  )
+}
+
+export default FenceMoveTool