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",