Add Notification Retry Statistics

[Abd-Standard]

Description

Track retry attempts for failed notifications to improve delivery monitoring.

Acceptance Criteria
Retry count is recorded.
Statistics are accessible.
Tests verify calculations.

[Abdul-dev-creator]

@Abdul-dev-creator has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

can i work on this pls?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Abdul-dev-creator to this issue.

[miss-yusrah]

@miss-yusrah has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Helloo Repo Maintainer, I'd like to work on this issue

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

[Caneryy]

@Caneryy has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi there, can I work on this issue?

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

[drips-wave]

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

🧑‍💻 @miss-yusrah: 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 🌊