Delete the call log's day folders older than a time, keeping what ratings
need (calls.md, "The folder"). Before a day goes, every rated call in it,
every call of its tree, every call its saw names and their ratings are
copied into one file at the folder's top level
(kept-<host>-<pid>-<hex>.jsonl), which every reader reads: a row of
rated made before pruning is made the same after. Returns how many day
folders and calls went, and how many calls were kept.
Delete the call log's day folders older than a time, keeping what ratings need (calls.md, "The folder"). Before a day goes, every rated call in it, every call of its tree, every call its
sawnames and their ratings are copied into one file at the folder's top level (kept-<host>-<pid>-<hex>.jsonl), which every reader reads: a row ofratedmade before pruning is made the same after. Returns how many day folders and calls went, and how many calls were kept.