Dryers report the same DrumCleanProposal_/WashingTimes_/DrumCleanLog_
options[] tokens washer.py already models for issue #9, so
drum_clean_cycles_remaining/drum_clean_last_cleaned move to laundry.py and
get bound on dryer's /course/vs/0 too.
DrumCleanLog_ on the reporter's dump is a '|'-joined history of every past
clean rather than washer's single bare timestamp -- the shared helper now
takes the last (most recent) entry, which turns out to also fix a latent
bug on four existing washer fixtures whose own DrumCleanLog_ was already
multi-entry and silently failing to parse into drum_clean_last_cleaned.
No heat-exchanger-clean tracking was found in either dump #258 supplied;
noted in dryer.py so a future report knows this was checked.