Add cnpg-option-a-backup JSON runner, vendored static age, kubectl install
helper, and ESO policy path for offsite lane so railiance01 workers can
upload without workstation OIDC (RAILIANCE-WP-0016).
Add workload KV lane for Nextcloud WebDAV token, URL, and age recovery
escrow at platform/workloads/railiance/backup/offsite-lane. Apply read
policy and OIDC role railiance-backup-workload-kv-read; wire forgejo-backup
to load credentials from OpenBao when env is unset.