feat: show real on-disk tracklist in the Library album modal (#9)

The Library modal showed MusicBrainz's canonical tracklist, hiding incomplete
downloads / edition or track-order mismatches, and showed nothing for albums
without an rgMbid. Now it shows the REAL files on disk.

- LibraryItem gains trackNames String[] (migration add_library_track_names):
  the album's on-disk "## Title.ext" audio filenames.
- Captured at import (pipeline._import lists the final album folder) and at scan
  (scan._record_owned now also refreshes trackNames on re-scan via ON CONFLICT
  DO UPDATE + xmax=0 to preserve the newly-imported flag). New shared
  library.list_audio_files() helper.
- /api/library exposes trackNames; the AlbumModal prefers on-disk tracks when
  present (parsed "## Title" → position/title, zero network, labeled "On disk ·
  N tracks"), falling back to the MusicBrainz listing otherwise. Items imported
  before this column show the MB fallback until re-scanned.

worker 221 tests / 7-skip, web 153, tsc + build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/lyra_worker/pipeline.py

@@ -9,7 +9,7 @@ import psycopg
 
 from lyra_worker.adapters.base import SourceAdapter
 from lyra_worker.confidence import score_confidence
-from lyra_worker.library import album_dir, import_album, staging_dir
+from lyra_worker.library import album_dir, import_album, list_audio_files, staging_dir
 from lyra_worker.quality import quality_class
 from lyra_worker.ranker import rank_candidates
 from lyra_worker.types import Candidate, MBTarget
@@ -186,18 +186,19 @@ def _mark_chosen(conn: psycopg.Connection, job_id: str, source_ref: str) -> None
 def _import(conn: psycopg.Connection, job_id: str, target: MBTarget,
             winner: Candidate, path: str) -> None:
     request_id = _request_id(conn, job_id)
+    track_names = list_audio_files(path)  # the real files just imported into the album folder
     with conn.cursor() as cur:
         cur.execute(
             'INSERT INTO "LibraryItem" (id, "requestId", artist, album, path, source, '
-            'format, "qualityClass", "importedAt") '
-            "VALUES (gen_random_uuid()::text, %s, %s, %s, %s, %s, %s, %s, now()) "
+            'format, "qualityClass", "trackNames", "importedAt") '
+            "VALUES (gen_random_uuid()::text, %s, %s, %s, %s, %s, %s, %s, %s, now()) "
             'ON CONFLICT (artist, album) DO UPDATE SET '
             '  "requestId" = EXCLUDED."requestId", path = EXCLUDED.path, source = EXCLUDED.source, '
             '  format = EXCLUDED.format, "qualityClass" = EXCLUDED."qualityClass", '
-            '  "importedAt" = now() '
+            '  "trackNames" = EXCLUDED."trackNames", "importedAt" = now() '
             'WHERE EXCLUDED."qualityClass" > "LibraryItem"."qualityClass"',
             (request_id, target.artist, target.album, path, winner.source,
-             winner.quality.fmt, quality_class(winner.quality)),
+             winner.quality.fmt, quality_class(winner.quality), track_names),
         )
         cur.execute(
             "UPDATE \"Request\" SET status = 'completed' WHERE id = %s", (request_id,)