Thread backup data connection fields through management command messages,
ManagementActor handlers, SiteService, site-side SQLite storage, and
deployment/replication actors. The old --configuration CLI flag is kept
as a hidden alias for backwards compatibility.
Add SiteReplicationActor (runs on every site node) to replicate deployed
configs and store-and-forward buffer operations to the standby peer via
cluster member discovery and fire-and-forget Tell. Wire ReplicationService
handler and pass replication actor to DeploymentManagerActor singleton.
Fix 5 pre-existing ConfigurationDatabase test failures: RowVersion NOT NULL
on SQLite, stale migration name assertion, and seed data count mismatch.
