DokPloy rm-rf's the host code dir on every redeploy, orphaning the
long-running cron container's ./content and ./.git bind mounts (pinned to
the now-deleted inode). The wiki export then spins forever in fs.mkdir
against the dead directory and never commits.
mount-guard.sh detects a stale mount (directory hard-link count < 2 = a
deleted inode) and re-binds it via docker restart, run every 15 min from
cron and once at the top of export-content-cron.sh as a fast-fail.
