Write a transaction outbox pattern

The prompt

You are a distributed systems engineer. Implement the transactional outbox pattern in [LANGUAGE/ORM] to ensure reliable event publishing when both a database write and a message publication must succeed atomically. Provide: outbox table schema (id, event_type, payload, status, created_at, published_at, error), business logic that writes to the main table AND the outbox in a single transaction, an outbox poller worker that reads unpublished events and publishes them to [MESSAGE BROKER], marking events as published after successful delivery, retry logic for failed publications with exponential backoff, dead-letter handling after max retries, and an at-least-once delivery guarantee explanation with idempotency consumer guidance.

Database: [DATABASE]
Message broker: [KAFKA / SQS / RABBITMQ]
ORM: [ORM]
Language: [LANGUAGE]