feat: download lifecycle — stalled and failed downloads are given up and searched again; imported ones seed, then go (M502 #5523)

Ported from Fabled Librarian's System 104. A new lifecycle poller, every
ten minutes:
- a download the client fails is given up at once;
- one nobody shares, or still fetching its file list, past the stall
  setting (6 h) is asked for again three times, then given up;
- giving up removes the download with its files, holds the release back
  for a week (release_blocks.expires_at), ends the grab and searches the
  album again, with no limit per album;
- a running download the client stops listing for half an hour ends and is
  searched again, not held back; an empty list is not taken as gone;
- an imported download seeds to ratio 2.0 or 14 days, then is removed;
- a download the client would not remove is asked again every pass.

Every condition and act is one open row per (client, download, condition)
in download_interventions. Activity shows what is wrong with a download and
how often it was retried, why one ended, its seeding, and a banner for a
client that does not answer. A running download can be given up by hand
(set aside for good). The seed ratio, seed days and stall hours are on the
search settings card. The download client lookup moves to
acquire.DownloadClientFor, shared by the importer and the lifecycle.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/queries/imports.sql

@@ -51,6 +51,9 @@ UPDATE grabs
        import_updated_at = now(),
        import_forced = false,
        imported_at = CASE WHEN sqlc.arg(import_state)::text = 'imported' THEN now() ELSE imported_at END,
+       -- The files were copied, so an imported download goes on sharing
+       -- until the lifecycle removes it (#5523).
+       seeding = sqlc.arg(import_state)::text = 'imported',
        imported_files = sqlc.arg(imported_files),
        destination = sqlc.arg(destination),
        ended_at = CASE WHEN sqlc.arg(end_reason)::text <> '' THEN now() ELSE ended_at END,
@@ -110,21 +113,30 @@ SELECT DISTINCT COALESCE(t.disc_number, 1)::int AS disc, t.track_number::int AS
 
 -- name: ListGrabs :many
 -- The Wanted view's Activity tab: downloads waiting on a person first, then
--- the rest still running, then the ended ones newest first.
+-- the rest still running, then the ended ones newest first. Each carries
+-- what is wrong with it now, if anything (#5523).
 SELECT g.id, g.want_id, g.name, g.indexer, g.client, g.quality, g.origin, g.forced,
        g.grabbed_at, g.ended_at, g.end_reason, g.end_detail, g.progress, g.import_state,
        g.import_reason, g.import_detail, g.import_updated_at, g.imported_at, g.imported_files,
-       g.destination, w.title AS want_title, w.artist_name AS want_artist
+       g.destination, g.seeding, g.ratio, g.seed_released_at,
+       w.title AS want_title, w.artist_name AS want_artist,
+       di.trigger AS condition, di.detail AS condition_detail, di.remediations AS condition_retries,
+       di.first_seen AS condition_since
   FROM grabs g
   LEFT JOIN wants w ON w.id = g.want_id
+  LEFT JOIN download_interventions di
+         ON di.id = (SELECT x.id FROM download_interventions x
+                      WHERE x.grab_id = g.id AND x.outcome = 'open'
+                      ORDER BY x.last_seen DESC LIMIT 1)
  ORDER BY (g.ended_at IS NULL AND g.import_state IN ('review', 'failed')) DESC,
           g.ended_at IS NULL DESC, g.grabbed_at DESC, g.id
  LIMIT sqlc.arg(max_rows) OFFSET sqlc.arg(skip);
 
 -- name: ListReleaseBlocksPage :many
-SELECT b.info_hash, b.name, b.reason, b.detail, b.blocked_at, w.title AS want_title,
+SELECT b.info_hash, b.name, b.reason, b.detail, b.blocked_at, b.expires_at, w.title AS want_title,
        w.artist_name AS want_artist
   FROM release_blocks b
   LEFT JOIN wants w ON w.id = b.want_id
+ WHERE b.expires_at IS NULL OR b.expires_at > now()
  ORDER BY b.blocked_at DESC, b.info_hash
  LIMIT sqlc.arg(max_rows) OFFSET sqlc.arg(skip);