OtOpcUa is Akka-clustered and AddZbSecrets is registered unconditionally, so every
node (admin, driver, fused) resolves secrets and needs the SAME KEK + same store rows.
Ship G-5 as a production-posture runbook rather than hardcoding Source=File + shared
paths into the committed role-overlay appsettings (which dev + TwoNodeClusterHarness
also consume — that would break every dev/CI boot). Base appsettings stays on
Source=Environment. Documents the interim File-KEK + shared-SQLite posture and the
G-7 hand-off (ConfigDb-backed ISecretStore mirroring the existing DP
PersistKeysToDbContext<OtOpcUaConfigDbContext> key-ring sharing). Cross-linked from
docs/security.md. Mirrors the ScadaBridge G-5 resolution.