- /pools: search by name, category/active filters, sort options and
pagination per the OpenAPI spec, with covers taken from each pool's
first post in one batched post call; blacklisted covers fall back to a
placeholder and deleted pools get an archive marker.
- /pools/<id>: DText description, post grid kept in the pool's own order
with chunked loading, in-library badges, a blacklist reveal toggle and
a Follow pool button wired into the follows API.
- e621 client gains fetchPools/fetchPool; Pools nav entry added.