Add Delivery Failure Reasons

[Abd-Standard]

Description

Record and expose the reason why a notification delivery failed.

Acceptance Criteria
Failure reason is stored.
Dashboard can retrieve the reason.
Documentation is updated.

[baling-1]

@baling-1 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello! I’d appreciate the opportunity to work on this issue. I’m an active contributor and can begin as soon as I’m assigned.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @baling-1 to this issue.

[whiteghost0001]

@whiteghost0001 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi! I'm a full-stack developer with experience building modern web applications using JavaScript/TypeScript, React, Next.js, Node.js, and blockchain technologies such as Stellar. I enjoy working on open-source projects, writing clean, maintainable code, and collaborating with the community.

I'd love to work on this issue. I believe I can contribute a high-quality solution, communicate my progress clearly, and submit a well-tested pull request. If the issue is still available, I'd appreciate being assigned to it. Thank you!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @whiteghost0001 to this issue.

[Lost-Z]

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

[drips-wave]

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

🧑‍💻 @Lost-Z: 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 🌊