feat: duplicates resolve themselves without Lidarr (M502 #5517)

Lidarr is off, and with it the resolver had stopped merging: it only
merged when Lidarr had said which copies it mapped. Minstrel is now the
only program writing the library, so the rule is about the copies:

- A song held twice on one album: the extra copies merge into the one
  whose tags fit best (then lossless, larger, older).
- Across releases or under another title: when every copy but one is a
  video rip (held back, or named like one and not marked fine), the rips
  merge into the one that is not.
- Clean copies on different releases are linked as one song, as before.
- Anything else waits for the operator.

Gone with Lidarr: release switches and their settle window, the
unmapped-file read, the rip search, the merge guard and its 409/503,
lidarr.Client's release methods, and duplicate_group_members.lidarr_state
(migration 0078). The duplicates page drops the per-copy Lidarr badge
and the blocked-merge notice; past release changes stay in its history.

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

internal/library/duplicate_survivor.go

@@ -14,10 +14,6 @@ type SurvivorCandidate struct {
 	FileSize   int64
 	AddedAt    time.Time
 
-	// LidarrTracked: Lidarr maps this file to a track of the release it
-	// monitors. Removing it opens a hole Lidarr downloads again (M498), so a
-	// tracked copy outranks everything else. False when Lidarr was not asked.
-	LidarrTracked bool
 	// TagFit is TagFitScore: how well the copy's tags and name fit the album.
 	TagFit int
 }
@@ -56,9 +52,9 @@ var losslessFormats = map[string]bool{"flac": true, "wav": true}
 // the report shows it and the merge (#3911) lets the operator choose another.
 //
 // In order:
-//  0. the copy Lidarr maps, then the copy whose tags fit the album best
-//     (TagFitScore). Both are zero for every copy when the caller does not
-//     know them, and the order falls through to the quality rules below
+//  0. the copy whose tags fit the album best (TagFitScore). It is zero for
+//     every copy when the caller does not know it, and the order falls through
+//     to the quality rules below
 //  1. lossless over lossy — the one difference no later step can recover
 //  2. the larger file — for one recording at one duration that is the higher
 //     bitrate. The scanner does not record bitrate (tracks.bitrate is never
@@ -81,8 +77,6 @@ func ProposeSurvivor(cands []SurvivorCandidate) (trackID, reason string) {
 	// runner-up — the rule that actually decided, not every rule it passed.
 	next := ranked[1]
 	switch {
-	case best.LidarrTracked != next.LidarrTracked:
-		return best.TrackID, "the copy Lidarr tracks"
 	case best.TagFit != next.TagFit:
 		return best.TrackID, "tags fit the album"
 	case isLossless(best) != isLossless(next):
@@ -97,9 +91,6 @@ func ProposeSurvivor(cands []SurvivorCandidate) (trackID, reason string) {
 }
 
 func survivorBefore(a, b SurvivorCandidate) bool {
-	if a.LidarrTracked != b.LidarrTracked {
-		return a.LidarrTracked
-	}
 	if a.TagFit != b.TagFit {
 		return a.TagFit > b.TagFit
 	}