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/elevator/floorplan.ts

@@ -326,7 +326,12 @@ export function buildElevatorFloorplan(
       { local: [outerHalfW + sideArrowOffset, 0], localAngle: 0, axis: 'x', side: 1 },
       { local: [-(outerHalfW + sideArrowOffset), 0], localAngle: Math.PI, axis: 'x', side: -1 },
       { local: [0, outerHalfD + sideArrowOffset], localAngle: Math.PI / 2, axis: 'z', side: 1 },
-      { local: [0, -(outerHalfD + sideArrowOffset)], localAngle: -Math.PI / 2, axis: 'z', side: -1 },
+      {
+        local: [0, -(outerHalfD + sideArrowOffset)],
+        localAngle: -Math.PI / 2,
+        axis: 'z',
+        side: -1,
+      },
     ]
     for (const side of sides) {
       const [ox, oz] = rotate(side.local[0], side.local[1])