🟡 HIGH: Add Kafka error handling (DLQ, retries)

[GitAddRemote]

Problem

Kafka integration lacks error handling:

• No error handler for @KafkaListener
• No dead letter queue
• No retry logic

Solution

1. Add DeadLetterPublishingRecoverer
2. Configure retry with backoff
3. Add error handler bean
4. Update consumer to use error handler

Acceptance Criteria

• DeadLetterPublishingRecoverer configured
• Retry logic with backoff
• DLT topic created automatically
• Tests for error scenarios
• Metrics for failed messages

Priority

🟡 High - Required for reliable event processing