fix(library): multi-genre local index with track_genre and backfill (#1059)

* fix(library): multi-genre local index with track_genre and backfill

Restore atomic genre browse, filters, and counts via track_genre:
OpenSubsonic genres[] first with Navidrome-default split fallback, sync
write path, read-path query switches, blocking startup backfill with
progress, and v12 repair migration for DBs that recorded legacy 002–011.
TS fallback adds genreTagsFor and migration gate i18n across locales.

* fix(library): address multi-genre review — robust TS genres and scope join

genreTagsFor routes raw genres through parseItemGenres (single-object
Subsonic quirk and bare strings). Library-scoped genre browse/counts join
track for raw_json library_id fallback. Statistics keeps empty-genre bucket.

* docs: CHANGELOG and credits for multi-genre local index (PR #1059)

* docs(changelog): credit HiveMind on Discord for multi-genre report (PR #1059)

src/locales/en/migration.ts

@@ -0,0 +1,15 @@
+export const migration = {
+  preparing: 'Preparing data update…',
+  preparingBody: 'Looking at your library and analysis cache…',
+  migrating: 'Migrating data',
+  working: 'working…',
+  skippedRows: 'Rows for removed servers were skipped and old backup DB will be removed after successful switch.',
+  failed: 'Migration failed',
+  retry: 'Retry',
+  copyDetails: 'Copy details',
+  complete: 'Update complete',
+  completeRows: '{{count}} rows migrated',
+  genreTagsTitle: 'Updating genre index…',
+  genreTagsBody: 'Indexing genres for browse and filters. This runs once after upgrade.',
+  genreTagsFailed: 'Genre index update failed',
+};