v0.9.0 — Event Consumer and Retry Foundations

v0.9.0 — Event Consumption, Retry, and Idempotency Foundations

Highlights:

• Added OrderCreatedEvent consumer using RabbitListener
• Introduced Spring AMQP retry configuration with DLQ republish strategy
• Added idempotency guard to prevent duplicate event processing
• Added in-memory idempotency store for consumer-side duplicate protection
• Added consumer unit tests covering first processing, duplicate detection, and invalid payload handling

This release moves OrderFlow from publish-only messaging into actual event consumption and reliability-oriented processing foundations.