Publish user-completed integration payload to RabbitMQ after successful enrichment

[gbzarelli]

Summary

Add a dedicated RabbitMQ outbound integration payload when user enrichment succeeds.

Scope

• keep Kafka as the event-streaming mechanism
• publish a RabbitMQ user-completed payload after sendUserAddressUpdatedEvent(...) returns successfully
• keep RabbitMQ behind a dedicated output port/adapter
• document the architectural decision with a new ADR
• cover the flow in unit and acceptance tests

Notes

RabbitMQ in this change is for targeted integration payload delivery, not as a second event-streaming platform.