fix(dbtest,library): include quarantine tables in ResetDB; clarify DeleteTrackFile docstring

- dbtest.ResetDB.dataTables now truncates lidarr_quarantine + lidarr_quarantine_actions
  alongside the other M2-M4 data tables. Without this, M5b service tests would
  inherit residual state across runs.
- DeleteTrackFile godoc spells out the post-file/pre-DB failure window
  reconciles via the next library scan; the function is retry-safe by design,
  not atomic.

internal/dbtest/reset.go

@@ -49,6 +49,8 @@ var dataTables = []string{
 	"skip_events",
 	"play_sessions",
 	"sessions",
+	"lidarr_quarantine_actions",
+	"lidarr_quarantine",
 	"tracks",
 	"albums",
 	"artists",

internal/library/delete.go

@@ -27,7 +27,10 @@ var ErrTrackNotFound = errors.New("library: track not found")
 //  3. Delete the tracks row.
 //
 // Order matters: file first, then DB. If the file delete fails (permission,
-// I/O error), we leave the DB row alone so the admin can retry.
+// I/O error), we leave the DB row alone so the admin can retry. The reverse
+// failure mode — file gone, DB row still present — is recoverable: the next
+// library scan reconciles missing files by removing their tracks rows. So
+// the function is retry-safe rather than atomic, by design.
 func DeleteTrackFile(ctx context.Context, pool *pgxpool.Pool, trackID pgtype.UUID) error {
 	q := dbq.New(pool)
 	track, err := q.GetTrackByID(ctx, trackID)