A related list's cursor cost nothing, and a cursor is a free string: a replayed one read and
enriched without end. Every request now takes a slot of the user's daily cap — taken under a lock
before the work (`quota.claim_action`), so requests sent together cannot all pass the last free
one, and given back when the request fails outright (`quota.refund_action`). The live search's
scrape source takes its slots the same way.
A limit of 0 turns the feature off: a distinct 409 `related_disabled` / `search_disabled`, and
`/api/me` says `related_enabled` / `search_enabled` so the UI can leave it out.
A videos.list that fails no longer reads as an empty page: `ingest_candidates` raises, and the
search and the related list answer the refusal (the shared budget spent says "quota") instead of
"no results". The two routes' page loops are one (`_gather`).
`clear` deletes only what the caller found: a related list's rows carry no find, and any user
could name them.
It always said a live search spends the shared API quota, while the default source (the website's
own endpoint, scrape) spends none — the owner avoided a free search because of it. /api/me now names
the running search_source, and the tooltip names the cost under it: none for scrape (the enrich step
costs a unit or two), 100 units a page for the official API.
peter