0dfb4234 made every mode-less atomic write follow the process umask for NEW
targets, restoring what open("w")-based writers did. Ten of the folded sites
were not open("w") writers: they created the file through mkstemp and never
chmod'd, so on main a fresh file was 0600 regardless of umask (bot mailboxes,
relay inbox, turn markers, sessions.json, cron jobs/output, banner snapshot,
plugin toolset cache, presets, shell hooks, install id). CI caught the loosening
in tests/tools/test_bot_live_owner_delivery.py (st_mode 0o077 bits set).
Pass mode=0o600 explicitly at those ten sites; the umask default stays for the
sites that were open("w") on main. Invariant test exercises two real writers.
9b6dcad91d