MongoDB backend (DD-07, DD-11): state, inbox, audit and outbox via mongodb-driver-sync, with a single multi-document transaction on a replica set and a documented single-document fallback for a standalone server, plus a stored rule set source and a task store.

Spring Boot starter (DD-13): one dependency and a `lifecycle.*` YAML block wire guards, rule sources, the store, the transport, the engine, the dispatcher, tasks, and the actuator surface.