feat: duplicates resolve themselves where Lidarr says it is safe (M498)

The duplicate sweep proposed 4,197 groups and every one waited for the
operator. Most are safe to settle, and Lidarr defines what safe means: it
maps one file to each track of the release it monitors and downloads any
mapped file that disappears. Deleting a mapped copy opens exactly the hole
the operator saw Lidarr fill.

Classify (#5435)
- Migration 0075: duplicate_groups.class (same_release, cross_release,
  mismatch, review), resolve_note, resolved_automatically;
  duplicate_group_members.lidarr_state (tracked, unmapped);
  fingerprint_settings.auto_resolve; notification kind
  duplicates_resolved with both kind CHECKs swapped (rule 36).
- library.ClassifyDuplicateGroup, with MatchTitleKey dropping featuring
  credits, remaster notes and video-rip markers, and keeping live, demo,
  remix and instrumental. The rip markers move from api to library.

Choose the copy to keep (#5436)
- ProposeSurvivor ranks the copy Lidarr maps first, then tag fit (a
  clash-free track number, no rip marker in the name, an MBID), then the
  quality rules. File size picked the wrong Humanz copy in 6 of 21 groups.

Act (#5437)
- An hourly resolver pass reads Lidarr's unmapped files, matched by the
  last three path components, and records each copy's state.
- Same album, with at most one copy mapped: merged into the mapped copy.
  The merge is guarded, so a mapped copy can never be removed
  (MergeDuplicateGroupGuarded, ErrCopyTrackedByLidarr).
- Same album, every copy mapped: the monitored release lists the song
  twice (Humanz's 14x12" box set). The pass moves Lidarr to the release
  that lists each song once and best covers what is on disk. It never
  picks one covering less, and is capped at 10 albums per pass.
  - Fixed point (lesson #4183): the chosen release no longer repeats.
  - The album is left alone for 24h while Lidarr rescans, so "every copy
    unmapped" mid-rescan is never read as licence to merge.
- Both actions are audited with no actor and summarised to admins. The
  operator can switch them off in the Fingerprinting card (rule 25).
- Manual merges use the same guard: 409 copy_tracked_by_lidarr, or 503
  lidarr_unavailable when Lidarr cannot say.

Web
- Duplicates gets tabs: Needs review, Across releases, Resolved
  automatically. Each loads as you scroll (rule 172), replacing the
  pager.
- Each copy says whether Lidarr uses it.
- The resolver's note shows on each group.
- The merge confirm blocks, before sending, a merge that would remove
  the copy Lidarr uses.

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

internal/notifications/kinds.go

@@ -9,8 +9,9 @@
 package notifications
 
 // Kind names one sort of notification. The set is CHECK-gated in migration
-// 0073 (rule 36): a new kind adds its value there, in the same change, and
-// TestKindsMatchMigrationCheck fails until it does.
+// 0073, swapped since by 0075 (rule 36): a new kind adds its value in a
+// migration of the same change, and TestEveryKindPassesTheSchemaChecks
+// fails until it does.
 type Kind string
 
 const (
@@ -22,7 +23,11 @@ const (
 	KindScanFailed        Kind = "scan_failed"
 	KindTracksMissing     Kind = "tracks_missing"
 	KindDuplicatesFound   Kind = "duplicates_found"
-	KindPlaybackErrors    Kind = "playback_errors"
+	// KindDuplicatesResolved: the duplicate resolver (M498) merged copies or
+	// changed a Lidarr release on its own. The operator asked for that to
+	// happen automatically; this is how it stays visible.
+	KindDuplicatesResolved Kind = "duplicates_resolved"
+	KindPlaybackErrors     Kind = "playback_errors"
 )
 
 // Audience is who a kind can reach. Admin kinds are never offered to, or
@@ -77,6 +82,9 @@ type spec struct {
 var (
 	allOn       = Channels{Inbox: true, Phone: true, Email: true}
 	healthAlert = Channels{Inbox: true, Phone: true, Email: false}
+	// inboxOnly: news an admin may want to read but never needs to be
+	// interrupted for.
+	inboxOnly = Channels{Inbox: true}
 )
 
 var specs = map[Kind]spec{
@@ -88,7 +96,9 @@ var specs = map[Kind]spec{
 	KindScanFailed:        {audience: AudienceAdmin, coalesce: true, sumCount: true, group: EmailBatch, defaults: healthAlert},
 	KindTracksMissing:     {audience: AudienceAdmin, coalesce: true, sumCount: true, group: EmailBatch, defaults: healthAlert},
 	KindDuplicatesFound:   {audience: AudienceAdmin, coalesce: true, group: EmailBatch, defaults: healthAlert},
-	KindPlaybackErrors:    {audience: AudienceAdmin, coalesce: true, group: EmailBatch, defaults: healthAlert},
+	// Each pass reports what it did itself, so the counts add up.
+	KindDuplicatesResolved: {audience: AudienceAdmin, coalesce: true, sumCount: true, group: EmailBatch, defaults: inboxOnly},
+	KindPlaybackErrors:     {audience: AudienceAdmin, coalesce: true, group: EmailBatch, defaults: healthAlert},
 }
 
 // order is the display order for settings screens: the requester's own kinds
@@ -102,6 +112,7 @@ var order = []Kind{
 	KindScanFailed,
 	KindTracksMissing,
 	KindDuplicatesFound,
+	KindDuplicatesResolved,
 	KindPlaybackErrors,
 }