Without rotation, the syslog listener and per-host collector grow
/var/log/decnet/ without bound — a noisy attacker (or an active
probe storm) fills the disk in hours on a small VPS. New
deploy/logrotate.d/decnet caps at 7 daily rotations or 100 MiB,
whichever comes first, and uses copytruncate because the ingester
and forwarder hold the files open via Python and won't reopen on
a rename rotation.
Wire install / remove into `decnet init` and `decnet init --deinit`
alongside the existing tmpfiles.d / polkit handling.