Add retention policies + cleanup jobs for auth_nonces, DLQ, processed events

[robertocarlous]

Problem

Tables like auth_nonces, processed_events, dead_letter_events, and agent_logs can grow without bound. This degrades performance and increases costs.

Acceptance criteria

• Add scheduled cleanup jobs:
  • delete expired auth_nonces
  • archive or prune old processed_events (configurable retention)
  • retention strategy for agent_logs (configurable)
• Add indexes where required for cleanup queries
• Add metrics: rows deleted, job duration, last successful run
• Document retention defaults and how to override via env

model AuthNonce { ... expiresAt ... }

Priority

P1 / High

[web3nova]

I've reviewed the issue description, and I'm confident I can implement all the requested details smoothly.​Please assign this issue to me! I can have a PR ready for review in a few hours. Thanks

[web3nova]

I've reviewed the issue description, and I'm confident I can implement all the requested details smoothly.​Please assign this issue to me! I can have a PR ready for review in a few hours. Thanks

[Nanle-code]

Hey,
Let me work on this issue

[grantfox-oss]

🦊 GrantFox — @Nanle-code has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #161)
2. Your PR will be reviewed by the Neurowealth maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

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

@Nanle-code's PR #182 was approved and merged by @robertocarlous.

🏆 @Nanle-code: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (83 total points). Track your full progress on GrantFox.

👏 Great work, @Nanle-code! Keep contributing to Neurowealth.