wkd_sync/archlinux-keyring-wkd-sync.service: Add hardened systemd service to run WKD sync using `archlinux-keyring-wkd-sync`.
wkd_sync/archlinux-keyring-wkd-sync: Add script to refresh existing keys of archlinux-keyring on user systems based on the state of the distribution's Web Key Directory (WKD). Invalid or revoked keys are ignored.