fix: handle TorBox 'checking' state as downloading, add symlink completion logging

- Add 'checking' to the list of downloading states in getTorboxStatus()
  so TorBox torrents in transitional state don't get marked as error
- Add debug log before calling onSuccess to trace state update flow

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/wire/torrent.go

@@ -235,6 +235,10 @@ func (s *Store) processFiles(torrent *Torrent, debridTorrent *types.Torrent, imp
 			onFailed(err)
 			return
 		}
+		s.logger.Debug().
+			Str("torrent_name", debridTorrent.Name).
+			Str("symlink_path", torrentSymlinkPath).
+			Msg("Symlink processing complete, calling onSuccess")
 		onSuccess(torrentSymlinkPath)
 		return
 	case "download":