[JOBS]: Introduce a transactional outbox and durable background worker

[barry01-hash]

Context

Emails, notifications, audit records, storage cleanup, and blockchain reconciliation are side effects of database changes. Executing them inline couples request success to external services; executing them after commit without durable coordination can lose work.

Scope

• Add an outbox model written in the same transaction as domain changes.
• Build a worker with atomic claiming, visibility timeout/lease, heartbeat, bounded retries, and dead-letter handling.
• Define versioned event payloads and idempotent consumers.
• Implement initial consumers for transactional email and one operational side effect.
• Add replay, inspection, and redrive tooling with audit records.
• Define retention and safe payload redaction.

Acceptance criteria

• A committed domain change always leaves durable side-effect work.
• Rolling back the domain transaction creates no outbox event.
• Worker crashes and duplicate delivery do not duplicate logical side effects.
• Poison messages stop retrying and remain inspectable/redrivable.
• Queue depth, oldest age, attempts, and failures are observable.
• Integration tests exercise concurrent workers and crash recovery.

Relevant areas

Prisma models, payout/application/support mutations, email-service.ts, future notifications and escrow reconciliation.