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/definition.ts

@@ -80,6 +80,13 @@ export const fenceDefinition: NodeDefinition<typeof FenceNode> = {
     // actions/move-endpoint.ts (linked-fence cascade, alt-detach,
     // single-undo dance). Wrapper owns the angle label + detach badge.
     'move-endpoint': () => import('./move-endpoint-tool'),
+    // Triggered by useEditor.movingNode when the moving node is a
+    // fence. Whole-fence rigid translation with linked-fence cascade.
+    // Pure logic in actions/move.ts uses the live-drag exception
+    // (mesh.position + useLiveTransforms) to avoid rebuilding fence
+    // geometry every pointer tick; commits the final start/end with
+    // the single-undo dance.
+    move: () => import('./move-tool'),
   },
 
   toolHints: [