feat(database): shape the library like files, and shrink the catalog

Plans 013 and 014, the album page that prompted them, and the smaller
fixes they turned up. Changelog, largest first.

## The local library is shaped like files, not like MusicBrainz

`audio_files` carries its own tags and points at `albums` and
`artists`; `file_genres` is the one real many-to-many. `recordings`,
`release_group_recordings`, `artist_credit`, `artist_credit_artist`,
`recording_genres`, `release_groups` and `release_to_rg` are gone from
the local side, and with them a six-way join in every read, a
`MIN(release_group_id)` subquery in eleven queries and a
first-credited-artist subquery in nine. Measured on a real 25,966-file
library, every many-to-many that model expressed was 1:1 in the data.

- Ownership is a file. `GetFilePathsByRecordingMBIDs`,
  `LibraryMBIDIndex.CheckMBIDs`, `collectLibraryEntities` and
  `pruneStaleLocalCrossReferences` all join `audio_files`, so the 812
  orphaned recordings, 216 release groups and 260 artists that library
  carried are now structurally impossible.
- One projection: every track query selects from the `track_metadata`
  view, one row type, one mapper. Nine hand-rolled copies had drifted
  far enough to report different years on different screens.
- `library_id = 0` means every library, so each list query exists once
  instead of scoped and unscoped with a branch at every call site.
- No migration chain. `sql/schemas/` is the one description of the
  shape; `sql/migrations/`, `applyMigrations` and `schema_migrations`
  are squashed away, along with the drift between them that had sqlc
  generating against a stale schema.
- `database.InsertTestTrack` is the one test seeder; twenty test files
  had been assembling the old FK chain each in its own order.

## The catalog stores its ids as bytes

`explore_index`'s three 36-char MBID columns and its entity-type text
are 16 raw bytes and a small integer. The table and its six indexes go
780 MB to 405 MB on a real 2,052,200-row catalog, which is why a fresh
install is ~0.6 GB rather than ~1.0 GB.

- `backend/explore/mbid.go` is the only place the encoding is known;
  everything above it speaks dashed strings.
- `CHECK(length(mbid) = 16)` makes a stringly write fail at the insert
  rather than silently returning no rows, since SQLite does not coerce
  between TEXT and BLOB.
- The importer asks the artifact what encoding it carries and converts
  on the way in, so the artifact already published keeps working and no
  format bump is needed.
- `indexRowColumns`/`scanIndexRow` replace four copies of a 22-column
  list, and `TestStoredEncodingRoundTrips` sweeps every read path.

## An album page that says how much of the album is yours

- One question, asked once: is there a file. `filePaths` is filled by a
  single batched lookup when the tracklist settles, and the badge, the
  Play count, the dimmed rows and every menu item read it — replacing
  four claims of decreasing confidence that could show a green tick on
  an album whose every action did nothing.
- Play, Play 7 of 12, or no play button at all.
- `total_tracks` on `explore_index` (~2 bytes over 400,677 release
  groups) and on `audio_files` from tags that have always carried it:
  a complete MBID-matched album now makes no catalog call at all, where
  it used to spend the most expensive request the app makes.
- A merged cluster shows the running order the most releases agree on,
  and the version list marks the release you own rather than standing a
  synthetic entry in for it.
- `AlbumReleasesFailed`: a slow fetch is no longer reported as a failed
  one by a 12-second timer.
- Rows not in the library are dimmed in place (with `aria-disabled`)
  instead of the owned ones wearing a green tick and a legend.

## Caches and cover art get ceilings

- Only the three tiers of a cover are stored; the full-resolution copy
  nothing rendered was 1,134 MB of a 1.4 GB covers directory.
- One artist portrait is downloaded and the rest are remembered as
  URLs — 4.1 GB of a 5.3 GB cache was candidates no code path reads.
- `browsedArtBudget` and `httpCacheBudget` bound what an age cannot:
  the same install held art for 5,770 artists in a 1,301-artist
  library.
- `OrphanedArtistImagesJob` joined a bare MBID onto a sharded
  directory, so it deleted the rows that were the only record of the
  files it left behind. `explore.ArtistImageDir` is that layout's one
  definition now.

## The autotag queue asks whether there is work

`tagging_items` was a row per album folder, not a queue, and no query
read the `tag_status` column that held the answer. The four queue
queries ask the files, which matters most where it is least visible:
`startPrefetch` was scoring every album in a tagged library against
MusicBrainz.

## Phantom playlist tracks resolve in place

An M3U8 imported before its files leaves phantom rows; they now match
by path and fall back to position, keep their place in the playlist
when resolved, and pair best-first so two phantoms cannot claim the
same file.

## Playing a track plays the list it is in

Double-click, and Play on a single row's menu, queue the list as
displayed with `startIndex` on that row — the album page and the track
list used to queue one track and discard the album around it. A
multi-row selection still plays exactly itself.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AfVYUVExXsx1nSWrXN8mAh

backend/database/sql/sqlcgen/models.go

@@ -9,23 +9,24 @@ import (
 	"time"
 )
 
+type Album struct {
+	ID                 int64
+	Name               string
+	ArtistCredit       string
+	ArtistID           sql.NullInt64
+	Mbid               sql.NullString
+	Year               sql.NullInt64
+	OriginalYear       sql.NullInt64
+	CoverArtID         sql.NullInt64
+	PendingReleaseMbid sql.NullString
+}
+
 type Artist struct {
 	ID   int64
 	Name string
 	Mbid sql.NullString
 }
 
-type ArtistCredit struct {
-	ID   int64
-	Text string
-}
-
-type ArtistCreditArtist struct {
-	ID       int64
-	ArtistID int64
-	CreditID int64
-}
-
 type ArtistEnrichment struct {
 	ArtistMbid string
 	BrowsedAt  sql.NullTime
@@ -56,21 +57,31 @@ type ArtistMetadatum struct {
 type AudioFile struct {
 	ID                 int64
 	FilePath           string
-	LengthMilliseconds int64
+	LibraryID          int64
 	FileTypeID         int64
-	RecordingID        int64
+	LengthMilliseconds int64
 	SampleRate         int64
 	BitDepth           int64
 	Channels           int64
 	Bitrate            int64
 	FileSize           int64
+	Title              string
+	ArtistCredit       string
+	ArtistID           sql.NullInt64
+	AlbumID            sql.NullInt64
+	TrackNumber        sql.NullInt64
+	DiscNumber         sql.NullInt64
+	TotalTracks        sql.NullInt64
+	Year               sql.NullInt64
+	Composer           string
+	Comment            string
+	RecordingMbid      sql.NullString
 	Basename           string
-	LibraryID          int64
+	GroupKey           string
+	ModifiedAt         int64
 	PlayCount          int64
 	LastPlayed         sql.NullTime
 	TagStatus          string
-	GroupKey           string
-	ModifiedAt         int64
 }
 
 type CoverArt struct {
@@ -160,20 +171,21 @@ type ExploreChampionFt struct {
 
 type ExploreIndex struct {
 	ID                  int64
-	EntityType          string
-	Mbid                string
+	EntityType          int64
+	Mbid                []byte
 	Title               string
 	ArtistName          string
-	ArtistMbid          string
+	ArtistMbid          []byte
 	Aliases             string
 	Popularity          int64
 	ListenerCount       int64
 	Duration            int64
-	CaaReleaseMbid      string
+	CaaReleaseMbid      []byte
 	ReleaseName         string
 	PrimaryType         string
 	SecondaryTypes      string
 	ReleaseDate         string
+	TotalTracks         int64
 	ArtistType          string
 	Country             string
 	Disambiguation      string
@@ -197,6 +209,11 @@ type ExploreIndexMetum struct {
 	Value string
 }
 
+type FileGenre struct {
+	AudioFileID int64
+	GenreID     int64
+}
+
 type FileType struct {
 	ID        int64
 	Extension string
@@ -231,6 +248,14 @@ type Library struct {
 	AutotagWarningAcked int64
 }
 
+type Lyric struct {
+	AudioFileID   int64
+	Text          string
+	Source        string
+	RecordingMbid sql.NullString
+	FetchedAt     time.Time
+}
+
 type LyricsIndex struct {
 	Lyrics string
 }
@@ -291,48 +316,6 @@ type QueueTrack struct {
 	Position    int64
 }
 
-type Recording struct {
-	ID             int64
-	Name           string
-	ArtistCreditID int64
-	TrackNumber    sql.NullInt64
-	DiscNumber     sql.NullInt64
-	Year           sql.NullInt64
-	Genre          sql.NullString
-	Composer       sql.NullString
-	Lyrics         sql.NullString
-	Comment        sql.NullString
-	Mbid           sql.NullString
-}
-
-type RecordingGenre struct {
-	ID          int64
-	RecordingID int64
-	GenreID     int64
-}
-
-type ReleaseGroup struct {
-	ID                  int64
-	Name                string
-	CoverArtID          sql.NullInt64
-	AlbumArtistCreditID sql.NullInt64
-	Year                sql.NullInt64
-	TotalTracks         sql.NullInt64
-	TotalDiscs          sql.NullInt64
-	Mbid                sql.NullString
-	OriginalYear        sql.NullInt64
-	PendingReleaseMbid  sql.NullString
-}
-
-type ReleaseGroupRecording struct {
-	ID             int64
-	ReleaseGroupID int64
-	RecordingID    int64
-	TrackNumber    sql.NullInt64
-	DiscNumber     sql.NullInt64
-	TotalTracks    sql.NullInt64
-}
-
 type ReleaseToRg struct {
 	ReleaseMbid string
 	RgMbid      string
@@ -410,4 +393,6 @@ type TrackMetadatum struct {
 	ArtistMbid         string
 	ReleaseGroupMbid   string
 	RecordingMbid      string
+	AlbumID            sql.NullInt64
+	ArtistID           sql.NullInt64
 }