feat(10-01): update SQL schema files for multi-library fresh installs

- Create _libraries.sql with libraries table (name, path, created_at)
- Add library_id FK column and index to audio_files.sql
- Update playlist_tracks.sql with nullable audio_file_id, SET NULL FK, and 6 phantom columns
- Add af.library_id to track_metadata VIEW
- Regenerate sqlc code for updated schemas
- Fix playlist.go to use sql.NullInt64 for nullable audio_file_id

backend/playlist/playlist.go

@@ -3,6 +3,7 @@ package playlist
 
 import (
 	"context"
+	"database/sql"
 	"errors"
 	"fmt"
 	"log/slog"
@@ -867,7 +868,7 @@ func (s *Service) ImportPlaylist(
 			s.db.Ctx,
 			sqlcgen.AddPlaylistTrackParams{
 				PlaylistID:  created.ID,
-				AudioFileID: audioFile.ID,
+				AudioFileID: sql.NullInt64{Int64: audioFile.ID, Valid: true},
 				Position:    int64(position),
 			},
 		)
@@ -1065,7 +1066,7 @@ func (s *Service) restoreSinglePlaylist(
 			s.db.Ctx,
 			sqlcgen.AddPlaylistTrackParams{
 				PlaylistID:  playlistID,
-				AudioFileID: audioFile.ID,
+				AudioFileID: sql.NullInt64{Int64: audioFile.ID, Valid: true},
 				Position:    int64(position),
 			},
 		)
@@ -1125,7 +1126,7 @@ func (s *Service) addSingleTrack(
 		s.db.Ctx,
 		sqlcgen.AddPlaylistTrackParams{
 			PlaylistID:  playlistID,
-			AudioFileID: audioFile.ID,
+			AudioFileID: sql.NullInt64{Int64: audioFile.ID, Valid: true},
 			Position:    position,
 		},
 	)
@@ -1654,7 +1655,7 @@ func (s *Service) ResolvePhantomTracks(
 			s.db.Ctx,
 			sqlcgen.AddPlaylistTrackParams{
 				PlaylistID:  playlistID,
-				AudioFileID: audioFile.ID,
+				AudioFileID: sql.NullInt64{Int64: audioFile.ID, Valid: true},
 				Position:    nextPos + int64(resolved),
 			},
 		)