Two driver nodes replicate the deployment-artifact cache over a real loopback
h2c transport through the real fail-closed LocalDbSyncAuthInterceptor; both DBs
init via the production LocalDbSetup.OnReady. Scenarios: byte-identical
convergence with matching pointer HLC+origin, retention prune reaching B as
tombstones, writes-while-transport-down surviving rejoin, and wrong-key
non-convergence with a matching-key positive control.
DoD positive control: commenting out both RegisterReplicated calls turns all
four scenarios red (verified locally, restored before commit).