Central Dogma: Hard-coded ZooKeeper replication secret 'ch4n63m3' with silent fallback enables cluster takeover

A vulnerability has been identified in centraldogma-server versions prior to 0.84.0, where enabling ZooKeeper replication without setting replication.secret causes the server to silently fall back to a hard-coded, publicly known secret. This default credential authenticates the embedded ZooKeeper ensemble, allowing an attacker with network access to read the full replication log or join the quorum and execute arbitrary replicated commands across the cluster.