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/nodes/src/stair/definition.ts

@@ -1,8 +1,8 @@
 import {
   type HandleDescriptor,
   type NodeDefinition,
-  type StairNode as StairNodeType,
   StairNode as StairNodeSchema,
+  type StairNode as StairNodeType,
 } from '@pascal-app/core'
 
 const MIN_CURVED_RISE = 0.3
@@ -223,11 +223,7 @@ function stairRotateGizmoPosition(n: StairNodeType): [number, number, number] {
   }
   const width = Math.max(n.width ?? 1, MIN_CURVED_WIDTH)
   const yMid = Math.max(n.totalRise ?? 2.5, 0.1) / 2
-  return [
-    width / 2 + STAIR_ROTATE_CORNER_OFFSET,
-    yMid,
-    -STAIR_ROTATE_CORNER_OFFSET,
-  ]
+  return [width / 2 + STAIR_ROTATE_CORNER_OFFSET, yMid, -STAIR_ROTATE_CORNER_OFFSET]
 }
 
 function stairRotateHandle(): HandleDescriptor<StairNodeType> {
@@ -288,6 +284,8 @@ function stairHandles(node: StairNodeType): HandleDescriptor<StairNodeType>[] {
   handles.push(stairRotateHandle())
   return handles
 }
+
+import { buildStairFloorplan } from './floorplan'
 import {
   curvedStairInnerRadiusAffordance,
   curvedStairSweepAffordance,
@@ -296,7 +294,6 @@ import {
   segmentWidthAffordance,
   stairRotateAffordance,
 } from './floorplan-affordances'
-import { buildStairFloorplan } from './floorplan'
 import { stairFloorplanMoveTarget } from './floorplan-move'
 import { stairParametrics } from './parametrics'
 import { StairNode } from './schema'