WP-0004 rewritten: scope narrowed to S2-owned assets (etcd snapshots,
Helm values, kubeconfig). No external dependencies. age encryption
reuses SOPS key pair. Output to /opt/backup/railiance/cluster/.
DECISIONS.md D4: integrated backup per capability, not centralized.
EP-RAIL-005 registered in state hub: custodian orchestration deferred
until all layers implement the standard interface.
The old monolithic backup (custodian DB + operator config) was not S2's
concern and has been removed from this workplan scope.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>