feat: Lidarr searches for a better copy of a rip that has none (M498 #5447)

The operator chose option 2: an album holding a video rip that is the only
copy of its song is searched in Lidarr (AlbumSearch), at most once a week
and ten albums a pass. Lidarr grabs only when the quality profile allows an
upgrade, so nothing is removed and the rip stays held back either way.

- lidarr.Client.SearchAlbums posts the AlbumSearch command.
- ListAlbumsWithSoleCopyRips finds the albums: a held-back rip with no
  present clean copy sharing its song or its pending group, and not searched
  in the last week (audit action lidarr_rip_search).
- Suspect sources shows when Lidarr last searched the track's album.

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

internal/api/admin_suspect_sources.go

@@ -31,6 +31,9 @@ type suspectTrackView struct {
 	// first pass (M498 #5439). VerdictAt is when it was last set.
 	Verdict   *string `json:"verdict"`
 	VerdictAt *string `json:"verdict_at"`
+	// SearchedAt is when the resolver last asked Lidarr to search the album for
+	// a better copy (#5447): null when it has not.
+	SearchedAt *string `json:"searched_at"`
 }
 
 // suspectGroupView is a folder's worth of flagged tracks. As on the
@@ -112,6 +115,10 @@ func groupSuspectByDirectory(rows []dbq.ListSuspectSourceTracksRow) []suspectGro
 			at := row.SourceVerdictAt.Time.UTC().Format(time.RFC3339)
 			t.VerdictAt = &at
 		}
+		if row.SearchedAt.Valid {
+			at := row.SearchedAt.Time.UTC().Format(time.RFC3339)
+			t.SearchedAt = &at
+		}
 		if n := len(groups); n > 0 && groups[n-1].Directory == row.Directory {
 			groups[n-1].Tracks = append(groups[n-1].Tracks, t)
 			continue