feat(paint-slots): round-2 feedback — fence 2 slots + UVs, roof defaults, stair body

- fence: split into two paint slots — panel (posts/base/infill, default charcoal)
  and rail (cap, default wood-finewood27) — as separate meshes with userData.slotId.
  Fix applyFenceUVs to continuous world-space 1 UV unit = 1 m (drop the per-part
  min origin that broke tiling across parts). New generateFenceSlotGeometries.
- roof: real catalog defaults for the segment surfaces via getRoofMaterialArray
  (the actual default path): wall/trim concrete-plate (matches walls), deck +
  soffit soft-white, shingle terracotta; textures-off role escape hatch kept.
  Align nodes getRoofMaterials no-parent fallback to match.
- stair: body slot default -> preset-lightgrey.
- (biome formatting normalization of the round-1 merged renderer files rides along.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/nodes/src/stair/renderer.tsx

@@ -160,9 +160,7 @@ export const StairRenderer = ({ node: rawNode }: { node: StairNode }) => {
           userData={STAIR_BODY_SLOT_USER_DATA}
         />
       ) : null}
-      {isSegmentBasedStair ? null : (
-        <CurvedStairBody bodyMaterials={bodyMaterials} stair={node} />
-      )}
+      {isSegmentBasedStair ? null : <CurvedStairBody bodyMaterials={bodyMaterials} stair={node} />}
       <StairRailings material={railingMaterial} stair={node} />
       {isSegmentBasedStair ? (
         <group name="segments-wrapper" visible={false}>