fix: media thumbnails, product dimensions, inline 3D viewer, GLB export

Bug A: Media Library thumbnails were gray because <img src> cannot send
JWT auth headers. Added useAuthBlob() hook (fetch + createObjectURL) in
MediaBrowser.tsx. Also fixed publish_asset Celery task to populate
product_id + cad_file_id on MediaAsset for thumbnail fallback resolution.

Bug B: Product dimensions now shown in Product Details card with Ruler
icon and "from CAD" label when cad_mesh_attributes.dimensions_mm exists.

Bug C: Replaced 128×128 CAD thumbnail with InlineCadViewer component.
Queries gltf_geometry MediaAssets, fetches GLB via auth fetch → blob URL
→ Three.js Canvas with OrbitControls. Falls back to thumbnail + "Load 3D
Model" button. Polling when GLB generation is in progress.

Bug D: trimesh was in [cad] optional extra but Dockerfile only installed
[dev]. Changed to pip install -e ".[dev,cad]" — trimesh now available in
backend container, GLB + Colors export works.

Also added bbox extraction (STL-first numpy parsing) in render_step_thumbnail
and admin "Re-extract CAD Metadata" bulk endpoint.

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

frontend/src/pages/CadPreview.tsx

@@ -21,7 +21,7 @@ export default function CadPreviewPage() {
   // Poll every 3s while generating so it appears automatically
   const { data: gltfAssets, isLoading: gltfLoading } = useQuery({
     queryKey: ['media-assets', id, 'gltf_geometry'],
-    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_type: 'gltf_geometry' }),
+    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_types: ['gltf_geometry'] }),
     enabled: !!id,
     staleTime: 5_000,
     refetchInterval: generating ? 3_000 : false,
@@ -30,7 +30,7 @@ export default function CadPreviewPage() {
   // Load production GLB if available
   const { data: productionAssets } = useQuery({
     queryKey: ['media-assets', id, 'gltf_production'],
-    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_type: 'gltf_production' }),
+    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_types: ['gltf_production'] }),
     enabled: !!id,
     staleTime: 30_000,
   })
@@ -38,7 +38,7 @@ export default function CadPreviewPage() {
   // Load blend assets for download
   const { data: blendAssets } = useQuery({
     queryKey: ['media-assets', id, 'blend_production'],
-    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_type: 'blend_production' }),
+    queryFn: () => getMediaAssets({ cad_file_id: id!, asset_types: ['blend_production'] }),
     enabled: !!id,
     staleTime: 30_000,
   })