feat(paint-slots): per-part paint for windows + doors, chrome/brass, world-scale UVs

Builds on the explicit per-mesh slot tagging (currentDoorSlot/currentWindowSlot):

- Per-part painting: door = panel/frame/glass/hardware, window = frame/glass,
  each independently paintable. The recessed door/window body sits behind the
  wall, so the proud invisible cutout wins the scene raycast over the wall and
  the shared resolveSlotByReRaycast() re-raycasts the kind's own subtree to pick
  the exact part under the cursor (panel↔frame↔glass↔hardware). Hover tracks the
  cursor via a  re-eval (idempotent, no flicker).
- Door frame is its own slot (separate frameMaterial); hardware = new flat
  'metal-chrome'.
- Library defaults (generic): panel/frame -> library:preset-softwhite, glass ->
  library:preset-glass (flipped preset-glass to FrontSide — DoubleSide poisons
  the WebGPU MRT pass; it's the only glass we use).
- Catalog: add flat (non-PBR) 'metal-chrome' + 'metal-brass'; drop metal
  metalness 1 -> 0.6 so metals are lit by existing lights (no env needed).
- World-scale UVs (1 unit = 1m) on door/window box meshes via shared box-uv.ts,
  so finishes tile at real-world scale instead of stretching.
- PaintResolveArgs gains an optional  for subtree re-raycasting.

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

packages/nodes/src/window/paint.ts

@@ -1,17 +1,16 @@
-import type { PaintResolveArgs } from '@pascal-app/core'
-import { createSlotPaintCapability, previewSlotByUserData } from '../shared/slot-paint'
+import {
+  createSlotPaintCapability,
+  previewSlotByUserData,
+  resolveSlotByReRaycast,
+} from '../shared/slot-paint'
 
 /**
- * Window paint on the unified slot model. The window's viewer system tags each
- * built mesh with `userData.slotId` (`frame` / `glass`), so the role resolves
- * straight from the pointer hit; commit writes `node.slots[slotId]`.
+ * Window paint on the unified slot model. The window's opening proxy (a proud,
+ * invisible cutout) wins the shared scene raycast over the wall in front of the
+ * recessed window, so `resolveSlotByReRaycast` re-raycasts the window's own
+ * subtree to find the part (frame / glass) under the cursor.
  */
-function resolveWindowRole(args: PaintResolveArgs): string | null {
-  const slotId = (args.hitObject?.userData as { slotId?: string | null } | undefined)?.slotId
-  return typeof slotId === 'string' ? slotId : null
-}
-
 export const windowPaint = createSlotPaintCapability({
-  resolveRole: resolveWindowRole,
+  resolveRole: resolveSlotByReRaycast,
   applyPreview: previewSlotByUserData,
 })

packages/nodes/src/window/slots.ts

@@ -4,8 +4,8 @@ export type WindowSlotId = 'frame' | 'glass'
 
 // Picker swatches. Rendering falls back to the live frame/glass defaults (which
 // already track shading + theme), so these are just the indicator colours.
-const FRAME_DEFAULT = '#f2f0ed'
-const GLASS_DEFAULT = '#87ceeb'
+const FRAME_DEFAULT = 'library:preset-softwhite'
+const GLASS_DEFAULT = 'library:preset-glass'
 
 /** A window exposes two paintable slots: the joinery frame and the glass. */
 export function windowSlots(): SlotDeclaration[] {