functions/runner: ensure data directory is not mounted before doing anything.
stage-pool/util-pacman-key.sh: add a stage for initializing pacman keychain.
stage-list-pool/3-install-system-primary/2-util-pacman-key.chroot.sh: add and shift stages.
stage-list{,-pool}: split 9999-cleanup into 9998-cleanup-dest and 9999-cleanup-host.
stage-pool/dest-install-configs@.sh: fix a typo.
export.sh: fix some minor things.