feat(paint-slots): prepared-drywall finish + fence 4 slots matching build options

- Add 'concrete-drywall' (Prepared Drywall) catalog finish + 512 KTX2/webp
  runtime assets; default walls (WALL_SLOT_DEFAULT interior+exterior) and the
  roof wall/trim band to it so roofs read continuous with walls.
- fence: replace the 2-slot panel/rail split with 4 slots that match the panel's
  build options — posts / infill (showInfill) / base (grounded only) / rail —
  each its own mesh with userData.slotId; conditional slots track the build
  state. Defaults: posts/infill/base charcoal, rail wood-finewood27.

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

packages/nodes/src/fence/slots.ts

@@ -1,15 +1,32 @@
 import type { SlotDeclaration } from '@pascal-app/core'
+import type { FenceNode } from './schema'
 
-export type FenceSlotId = 'panel' | 'rail'
+// Slots map 1:1 to the fence panel's build options: the end posts, the infill
+// slats (the showInfill toggle), the base kickboard, and the top rail.
+export type FenceSlotId = 'posts' | 'infill' | 'base' | 'rail'
 
-// Body (posts / base / infill) reads as a dark composite by default; the rail
-// cap as wood. Both are repaintable per slot.
-export const FENCE_PANEL_SLOT_DEFAULT = 'library:preset-charcoal'
+export const FENCE_POSTS_SLOT_DEFAULT = 'library:preset-charcoal'
+export const FENCE_INFILL_SLOT_DEFAULT = 'library:preset-charcoal'
+export const FENCE_BASE_SLOT_DEFAULT = 'library:preset-charcoal'
 export const FENCE_RAIL_SLOT_DEFAULT = 'library:wood-finewood27'
 
-export function fenceSlots(): SlotDeclaration[] {
-  return [
-    { slotId: 'panel', label: 'Panel', default: FENCE_PANEL_SLOT_DEFAULT },
-    { slotId: 'rail', label: 'Rail', default: FENCE_RAIL_SLOT_DEFAULT },
+export const FENCE_SLOT_DEFAULTS: Record<FenceSlotId, string> = {
+  posts: FENCE_POSTS_SLOT_DEFAULT,
+  infill: FENCE_INFILL_SLOT_DEFAULT,
+  base: FENCE_BASE_SLOT_DEFAULT,
+  rail: FENCE_RAIL_SLOT_DEFAULT,
+}
+
+export function fenceSlots(node: FenceNode): SlotDeclaration[] {
+  const slots: SlotDeclaration[] = [
+    { slotId: 'posts', label: 'Posts', default: FENCE_POSTS_SLOT_DEFAULT },
   ]
+  if (node.showInfill !== false) {
+    slots.push({ slotId: 'infill', label: 'Infill', default: FENCE_INFILL_SLOT_DEFAULT })
+  }
+  if (node.baseStyle !== 'floating') {
+    slots.push({ slotId: 'base', label: 'Base', default: FENCE_BASE_SLOT_DEFAULT })
+  }
+  slots.push({ slotId: 'rail', label: 'Rail', default: FENCE_RAIL_SLOT_DEFAULT })
+  return slots
 }