The create-path coercion (salvaged from #78928) left update_job and the
cronjob tool's update handler comparing/storing raw strings: repeat=
'forever' via update raised TypeError in the tool path and stored the raw
string via update_job, breaking the next mark_job_run ('str' has no
.get). Extract normalize_repeat_value as the shared chokepoint (shape
from #77366 by @andrexibiza, with garbage-rejection semantics) and route
create_job, update_job, and the tool update handler through it.
Completed counters are preserved across repeat updates.
Class: #66824#64520#7142#71987#95706, update half of #77366.
52e5e7c034