Add "reserved-slot expiry" webhook to notify suppliers of released holds

[thlpkee20-wq]

Description

Emit a supplier-facing webhook slot.reservation.expired whenever a slot hold is released due to booking-intent expiry, containing slot id, tz-aware start, and reason.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/webhooks/dispatch.ts, src/workers/expireBookingIntents.ts

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/slot-reservation-expired-webhook
• Implement changes
  • Add webhook event type + JSON schema
  • Dispatch on release with signature per existing webhook contract
  • Add supplier setting to opt in/out of this event
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • supplier opted-out (no dispatch), delivery failure retries with backoff, duplicate release (dedupe)
• Include test output and notes

Example commit message

feat: slot.reservation.expired webhook

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[Wizdee-001]

@Wizdee-001 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi, i would like to promptly work on this issue before 2:00pm with excellent result if assigned. thank you

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Wizdee-001 to this issue.

[greatest0fallt1me]

@greatest0fallt1me has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainers 👋,
I’m interested in picking up this issue and contributing to the project.
I have solid experience working across both frontend and blockchain layers, including building user interfaces with Next.js and developing Stellar smart contracts using Rust (Soroban). I’m familiar with translating Figma designs into pixel-accurate UIs, handling wallet integrations, and writing efficient, well-tested contract logic.
I focus on writing clean, maintainable code, following repository standards, and keeping communication transparent throughout the development process. I can start immediately and complete the work within the expected timeframe.
Excited to collaborate and add value to the project 🚀
Thank you!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @greatest0fallt1me to this issue.

[drips-wave]

Congratulations, @Wizdee-001! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @Wizdee-001: 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 🌊

[thlpkee20-wq]

Assigned to @Wizdee-001 based on their Drips Wave application. This assignment was checked against the limit of 4 active assigned issues without a linked PR across the Chronopay-Org organization. Please open a PR referencing this issue when ready.