Browser gets Textures/Models tabs (per-type catalog cache). Model file
JSON is parsed into per-set texture maps (generic set-prefix matching),
FBX is downloaded with resolution fallback, one URP/Lit material is
built per set via the shared PbrMaterialBuilder (which now returns the
created Material), and new ModelImportUtil remaps FBX material slots to
the built materials by set-name matching.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
New Tools/ambientCG Importer window (catalog browser, ZIP download with
selective map extraction, URP/Lit material build). Generic pieces moved
from the PolyHaven tool into Editor/WebAssets (EditorWebRequest,
PbrMapType, PbrMaterialBuilder, ImportUtil, AssetBrowserGrid); PolyHaven
API/window now delegate to the shared code, behavior unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>