- MediaItem gains e621_match_status (unknown/matched/not_found/deleted)
and e621_checked_at, backfilled for existing matched items.
- Server-side e621 client (apps/library/e621.py) using the user's stored
credentials, throttled to 2 req/s, with typed errors.
- Matching service: MD5 lookup, manual post linking (flags MD5
mismatches), unlink, metadata refresh, deleted-post detection.
- Detail actions POST /api/files/J-x/match/ and /unlink/ (uploader or
staff only).
- Background library scans: MatchTask + /api/matches/ with missing/all
scopes, progress polling, cancel and stale-task reaping; the scan
counts toward the footer's Active Workers. Same pass available as
manage.py match_e621 for cron.
- Library gains not_found/deleted status filters; the detail page adds
an e621 match card (check / link by post ID / unlink) and the metadata
card warns when a post was deleted on e621.
