List Grailed's facet taxonomy

Returns Grailed's full facet taxonomy for the enum-like parameters grailed-search/grailed-sold-listings accept: department, category, category_path (a more granular subcategory slug), condition, color, and size, each with its own live listing count. department and condition are exhaustive closed sets (2 and 5 values respectively); category/category_path/color/size are the full, exhaustive value space as of the request. Designer is NOT included here (7,363 values, far too large for a facet-count response) -- see grailed-designers for that discovery endpoint.