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/viewer/src/systems/fence/fence-system.tsx

@@ -150,15 +150,17 @@ function getStyleDefaults(style: FenceNode['style']) {
   return { spacingFactor: 0.3, postFactor: 0.55, baseFactor: 1, topFactor: 0.75 }
 }
 
-export type FenceSlotParts = {
-  /** Posts, base/kickboard, and vertical infill — the fence body. */
-  panel: FencePart[]
-  /** Top rail (and the floating style's matching bottom rail). */
-  rail: FencePart[]
-}
+// Paint slots map 1:1 to the fence panel's build options (Structure + the
+// showInfill toggle): the end posts, the infill slats between them, the base
+// kickboard, and the top rail.
+export type FenceSlotId = 'posts' | 'infill' | 'base' | 'rail'
+
+export type FenceSlotParts = Record<FenceSlotId, FencePart[]>
 
 function createFenceParts(fence: FenceNode): FenceSlotParts {
-  const panel: FencePart[] = []
+  const posts: FencePart[] = []
+  const infill: FencePart[] = []
+  const base: FencePart[] = []
   const rail: FencePart[] = []
   const length = Math.max(getWallCurveLength(fence), 0.01)
   const panelDepth = Math.max(fence.thickness, 0.03)
@@ -178,7 +180,7 @@ function createFenceParts(fence: FenceNode): FenceSlotParts {
   const endInsetT = Math.max(0.501, 1 - edgeInset / length)
 
   if (!isFloating) {
-    panel.push(
+    base.push(
       ...createFenceCurveSpanParts(
         fence,
         0,
@@ -188,7 +190,7 @@ function createFenceParts(fence: FenceNode): FenceSlotParts {
         panelDepth * 1.05,
       ),
     )
-    panel.push(
+    base.push(
       ...createFenceCurveSpanParts(
         fence,
         0,
@@ -213,7 +215,9 @@ function createFenceParts(fence: FenceNode): FenceSlotParts {
       : verticalHeight
     const postY = fullHeightPost ? postHeight / 2 : verticalY
 
-    panel.push({
+    // End posts are the structural `posts` slot; the intermediate verticals are
+    // the `infill` slats (only present when showInfill adds them).
+    ;(isEdgePost ? posts : infill).push({
       position: [frame.point.x, postY, frame.point.y],
       rotationY: -frame.tangentAngle,
       scale: [postWidth, postHeight, Math.max(panelDepth * 0.35, 0.012)],
@@ -244,7 +248,7 @@ function createFenceParts(fence: FenceNode): FenceSlotParts {
     )
   }
 
-  return { panel, rail }
+  return { posts, infill, base, rail }
 }
 
 function mergeFenceParts(parts: FencePart[]): THREE.BufferGeometry {
@@ -262,21 +266,26 @@ function mergeFenceParts(parts: FencePart[]): THREE.BufferGeometry {
 }
 
 /**
- * Geometry split by paint slot: the body (posts / base / infill) and the rail
- * cap, each a separate merged BufferGeometry so the fence renderer can give
- * each its own material + `userData.slotId`.
+ * Geometry split by paint slot — posts, infill, base, rail — each a separate
+ * merged BufferGeometry (empty ones included) so the fence renderer can give
+ * each its own material + `userData.slotId`. Slots match the panel's build
+ * options 1:1.
  */
-export function generateFenceSlotGeometries(fence: FenceNode): {
-  panel: THREE.BufferGeometry
-  rail: THREE.BufferGeometry
-} {
-  const { panel, rail } = createFenceParts(fence)
-  return { panel: mergeFenceParts(panel), rail: mergeFenceParts(rail) }
+export function generateFenceSlotGeometries(
+  fence: FenceNode,
+): Record<FenceSlotId, THREE.BufferGeometry> {
+  const parts = createFenceParts(fence)
+  return {
+    posts: mergeFenceParts(parts.posts),
+    infill: mergeFenceParts(parts.infill),
+    base: mergeFenceParts(parts.base),
+    rail: mergeFenceParts(parts.rail),
+  }
 }
 
 export function generateFenceGeometry(fence: FenceNode) {
-  const { panel, rail } = createFenceParts(fence)
-  return mergeFenceParts([...panel, ...rail])
+  const { posts, infill, base, rail } = createFenceParts(fence)
+  return mergeFenceParts([...posts, ...infill, ...base, ...rail])
 }
 
 function updateFenceGeometry(fenceId: FenceNode['id']) {

packages/viewer/src/systems/roof/roof-materials.ts

@@ -15,10 +15,10 @@ import {
 
 // Declared catalog defaults for an unpainted roof, per the 4-slot layout
 // (0 wall/trim · 1 deck · 2 interior soffit · 3 shingle top). The wall/trim
-// band mirrors the wall kind's default (WALL_SLOT_DEFAULT = concrete-plate) so
-// a roof reads as continuous with the walls below it.
+// band mirrors the wall kind's default (WALL_SLOT_DEFAULT = concrete-drywall)
+// so a roof reads as continuous with the walls below it.
 const ROOF_DEFAULT_REFS: [string, string, string, string] = [
-  'library:concrete-plate',
+  'library:concrete-drywall',
   'library:preset-softwhite',
   'library:preset-softwhite',
   'library:roof-terracottatiles',