Backend: Add policy-driven retention cleanup for stale idempotency records

[Junirezz]

Implement retention policies and cleanup jobs for stale idempotency records with metrics reporting.

[bamiebot-maker]

@bamiebot-maker has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

kindly assign this issue to me i am ready to start solving the issue and create a pr within a day

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[drips-wave]

Congratulations, @kingeligma! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @kingeligma: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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🌊 Happy Wave 🌊

[KingDavid9999]

@KingDavid9999 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I'd very much appreciate the opportunity to work on this issue.
Having reviewed the acceptance criteria, I'm confident that I'd be able to have a PR up shortly after being assigned.
Kindly assign this issue to me.
Thank you!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @KingDavid9999 to this issue.

[Menjay7]

@Menjay7 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi! I’m a full-stack developer with a strong blockchain background. I’d love to handle this issue and can deliver a clean, reliable solution. Kindly assign it to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Menjay7 to this issue.

[success-OG]

@success-OG has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hii, i'd like to work on this issue

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[Caneryy]

@Caneryy has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello! Can I work on this issue please?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Caneryy to this issue.

[drips-wave]

Congratulations, @success-OG! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @success-OG: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊