feat(editor): preset-system polish — paint panel, slim action bar, icon rail (#354)

* feat(editor): preset-system polish — paint panel, slim action bar, icon rail

- Export `MaterialPaintPanel` so embedders host the paint material picker in
  their own panel (community docks it in the Build sidebar) instead of the
  bottom action bar.
- ActionMenu: drop the build / material-paint / furnish modes and the
  structure-tools palette row + paint tray (the host's Build sidebar owns
  building now). Reduce `structure-tools` to the shared `tools` lookup still
  used by cursor/floorplan indicators; remove the orphaned `useContextualTools`.
- MaterialPicker: swatches wrap into a fluid `auto-fill` grid that fills width.
- IconRail (tab-bar): bigger icons, grayscale-when-idle, Radix tooltip, w-14
  rail; sync `RAIL_WIDTH` to 56.
- Inspector footer: hand the host `footer` to kind-owned custom panels via
  `InspectorFooterContext` so the save button renders without per-kind wiring.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* chore: biome format pass

Whole-repo formatter normalization (line wrap/unwrap only, no logic changes)
surfaced by the format-on-edit hook against prior drift. Kept separate from the
feature commit so the preset-system diff stays reviewable.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

packages/core/src/index.ts

@@ -102,8 +102,8 @@ export {
 } from './store/use-interactive'
 export {
   default as useLiveNodeOverrides,
-  type LiveNodeOverrides,
   getEffectiveNode,
+  type LiveNodeOverrides,
 } from './store/use-live-node-overrides'
 export { default as useLiveTransforms, type LiveTransform } from './store/use-live-transforms'
 export { clearSceneHistory, default as useScene } from './store/use-scene'

packages/core/src/registry/handles.ts

@@ -189,11 +189,7 @@ export type EndpointMoveHandle<N> = {
   endpoint: 'start' | 'end'
   placement: HandlePlacement<N>
   /** Called with the world-space hit on the ground plane. */
-  apply: (
-    node: N,
-    worldPoint: readonly [number, number, number],
-    sceneApi: SceneApi,
-  ) => Partial<N>
+  apply: (node: N, worldPoint: readonly [number, number, number], sceneApi: SceneApi) => Partial<N>
   portal?: HandlePortal
 }