CPython's allocator holds freed memory in arenas and doesn't return it to
the OS, causing RSS to grow throughout the 2015-activity loop even when
each iteration's objects are freed. Call gc.collect() + malloc_trim(0)
every 50 activities to return freed pages to the kernel and keep RSS flat.
The in-process approach loaded all 2015 Strava originals into the server
process memory, causing OOM kills. Now spawns `bincio reextract-originals`
as a child process; heavy work runs in an isolated Python interpreter that
exits when done, freeing all memory.
Also adds `bincio reextract-originals` as a standalone CLI command that
prints JSON-lines progress to stdout — useful for running directly on the
VPS via SSH for large backlogs.
Davide Scaini