Entities to fetch tags for, grouped by type: a list of { ids, type } groups. Each group binds its id list to a single type, so a group's ids only match tags of that type (no cross-product between ids and types across groups). Use this endpoint instead of GET /tags?filters=... for bulk lookups: the body has no URL-length limit. The total number of ids across all groups must not exceed 1000 (enforced in the handler).