Top-level supervisor for reckon-gater

Supervision Tree

reckon_gater_sup (one_for_one) - esdb_gater_cluster_sup (rest_for_one) - esdb_gater_worker_registry - esdb_gater_cluster_monitor - esdb_channel_sup (one_for_one) - 10x channel workers

Note: esdb_gater_api is a stateless API module, not a supervised process.