datetime.strptime sometimes fails in Kodi's embedded Python ('NoneType'
object is not callable), which aborted the whole guide export. Build the
XMLTV times without it.
The service now checks every 30 minutes and refreshes when the files are
over 6 hours old, so a failed refresh is retried soon. write_if_changed
touches an unchanged file so its time means "last refreshed".
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
