The canonical Oyster product taxonomy — the closed set of categories a product may be
filed under, and the list a vendor picks from. Retired legacy categories are never
returned, whatever their active flag says.

Only the categories Oyster carries are returned: the face and body groups, plus
Kits & Sets for now. Hair care, makeup, fragrance, supplements, tools & devices,
baby and grooming exist in the taxonomy so they can be recognised, but a product
filed under one of them is rejected at upload and never listed.

The taxonomy is flat, so parent_id and include_children are accepted for backwards
compatibility but can never match anything.