feat(PBR): extract Blender PBR properties and apply in 3D viewer

Extract Base Color, Metallic, Roughness, Transmission, IOR from Blender
asset library materials via catalog_assets.py. Store in catalog JSON and
serve via /api/asset-libraries/pbr-map endpoint. Frontend viewers apply
PBR properties to Three.js MeshStandardMaterial using hex color strings
(avoiding Three.js ColorManagement sRGB/linear issues).

Key fixes:
- RLS bypass for material alias lookup in pbr-map endpoint
- pbrMap empty guard prevents premature grey fallback in viewers
- Cache-Control: no-cache on pbr-map requests to avoid stale data

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/cad/MaterialPanel.tsx

@@ -4,35 +4,8 @@ import { X, Loader2, Palette, Layers, EyeOff } from 'lucide-react'
 import { toast } from 'sonner'
 import api from '../../api/client'
 import { savePartMaterials, saveManualOverrides, type PartMaterialMap, type PartMaterialEntry } from '../../api/cad'
-
-// ---------------------------------------------------------------------------
-// SCHAEFFLER_COLORS — viewport preview colors for known library materials
-// ---------------------------------------------------------------------------
-
-export const SCHAEFFLER_COLORS: Record<string, string> = {
-  'SCHAEFFLER_010101_Steel-Bare':         '#8a9ca8',
-  'SCHAEFFLER_010102_Steel-Polished':     '#b0c4ce',
-  'SCHAEFFLER_010103_Steel-Brushed':      '#9aabb5',
-  'SCHAEFFLER_010104_Steel-Painted':      '#607080',
-  'SCHAEFFLER_010201_Stainless-Bare':     '#adb9bf',
-  'SCHAEFFLER_010202_Stainless-Polished': '#cdd8dc',
-  'SCHAEFFLER_010301_Iron-Cast':          '#696969',
-  'SCHAEFFLER_020101_Aluminium-Bare':     '#c8c8c8',
-  'SCHAEFFLER_020102_Aluminium-Anodized': '#b0b8c0',
-  'SCHAEFFLER_030101_Brass':              '#c9a84c',
-  'SCHAEFFLER_030201_Bronze':             '#a07040',
-  'SCHAEFFLER_040101_Copper':             '#b87333',
-  'SCHAEFFLER_050101_Plastic-Black':      '#202020',
-  'SCHAEFFLER_050102_Plastic-White':      '#f0f0f0',
-  'SCHAEFFLER_050201_Rubber-Black':       '#1a1a1a',
-  'SCHAEFFLER_060101_Ceramic':            '#e8dcc8',
-  'SCHAEFFLER_070101_Glass':              '#88bbcc',
-}
-
-export function previewColorForEntry(entry: PartMaterialEntry): string {
-  if (entry.type === 'hex') return entry.value
-  return SCHAEFFLER_COLORS[entry.value] ?? '#888888'
-}
+import { fetchMaterialPBR, type MaterialPBRMap } from '../../api/assetLibraries'
+import { previewColorForEntry, pbrColorHex } from './cadUtils'
 
 // ---------------------------------------------------------------------------
 // MaterialOut — matches GET /api/materials response
@@ -68,6 +41,8 @@ export interface MaterialPanelProps {
   isPartKeyMode?: boolean
   /** Current manual overrides map (needed to merge when saving in partKey mode) */
   manualOverrides?: Record<string, string>
+  /** PBR material map from Blender asset library */
+  pbrMap?: MaterialPBRMap
 }
 
 export default function MaterialPanel({
@@ -82,9 +57,19 @@ export default function MaterialPanel({
   assignmentProvenance,
   isPartKeyMode = false,
   manualOverrides = {},
+  pbrMap: pbrMapProp,
 }: MaterialPanelProps) {
   const queryClient = useQueryClient()
 
+  // Fetch PBR data if not passed via props
+  const { data: pbrMapFetched } = useQuery({
+    queryKey: ['material-pbr'],
+    queryFn: fetchMaterialPBR,
+    staleTime: 300_000,
+    enabled: !pbrMapProp,
+  })
+  const pbrMap = pbrMapProp ?? pbrMapFetched ?? {}
+
   // Fetch all tenant materials (no filter — user sees their full library)
   const { data: allMaterials = [] } = useQuery({
     queryKey: ['materials'],
@@ -180,9 +165,12 @@ export default function MaterialPanel({
   }
 
   const isBusy = saveMut.isPending || removeMut.isPending || manualSaveMut.isPending || manualRemoveMut.isPending
+
+  // Preview color for selected material
+  const selectedPbr = pbrMap[libValue]
   const previewHex = assignType === 'hex'
     ? hexValue
-    : (SCHAEFFLER_COLORS[libValue] ?? '#888888')
+    : (selectedPbr ? pbrColorHex(selectedPbr) : '#888888')
 
   return (
     <div
@@ -304,13 +292,18 @@ export default function MaterialPanel({
           </div>
         )}
 
-        {/* Preview swatch */}
+        {/* Preview swatch with PBR info */}
         <div className="flex items-center gap-2 text-[11px] text-gray-400">
           <div
             className="w-4 h-4 rounded-sm border border-gray-600 shrink-0"
             style={{ backgroundColor: previewHex }}
           />
-          <span>Viewport preview color</span>
+          <span className="flex-1">Preview</span>
+          {assignType === 'library' && selectedPbr && (
+            <span className="text-[10px] text-gray-500 font-mono">
+              M:{selectedPbr.metallic.toFixed(1)} R:{selectedPbr.roughness.toFixed(1)}
+            </span>
+          )}
         </div>
 
         {/* Current assignment */}
@@ -318,7 +311,7 @@ export default function MaterialPanel({
           <div className="flex items-center gap-2 text-[11px] text-gray-400 bg-gray-800/60 rounded px-2 py-1.5">
             <div
               className="w-3 h-3 rounded-sm shrink-0 border border-gray-600"
-              style={{ backgroundColor: previewColorForEntry(currentEntry) }}
+              style={{ backgroundColor: previewColorForEntry(currentEntry, pbrMap) }}
             />
             <span className="truncate">Current: {currentEntry.value}</span>
           </div>