Add idempotency and durable retry-state handling to the queue layer

[grantfox-oss]

Prevent duplicate execution and improve operator recoverability by attaching idempotency keys, retry metadata, and bounded requeue behavior to background jobs.

• Affected files: app/backend/src/job-queue/job-queue.module.ts, app/backend/src/job-queue/, app/backend/src/exports/exports.service.ts, app/backend/src/reconciliation/, app/backend/src/notifications/notification-log.repository.ts, app/backend/src/links/recurring-payments.scheduler.ts, app/backend/src/marketplace/marketplace.service.ts, app/backend/test/queue.integration.spec.ts
• Acceptance criteria:
  • Replayed or retried jobs are recognized as duplicates and do not create conflicting side effects.
  • Failed jobs retain structured retry metadata for debugging and operator inspection.
  • Queue semantics and recovery expectations are documented and validated in integration tests.

[prismn]

Can you assign this issue to me ? i'd implement the idempotency and durable retry-state handling to the queue layer

[grantfox-oss]

🦊 GrantFox — @prismn has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #543)
2. Your PR will be reviewed by the BlockDash-Studios maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@prismn's PR #547 was approved and merged by @MaryammAli.

🏆 @prismn: You earned 40 FoxPoints for this contribution! Your current tier: Builder (1,065 total points). Track your full progress on GrantFox.

👏 Great work, @prismn! Keep contributing to BlockDash-Studios.