Add "supplier calendar sync" webhook to push slot changes to their external calendar

[thlpkee20-wq]

Description

Emit slot.changed webhooks to suppliers containing the calendar payload (start, duration, status) so they can sync into their own systems, with the calendar.mode field indicating whether it was an add/update/delete.

Requirements and context

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

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/supplier-calendar-webhook
• Implement changes
  • Add slot.changed webhook event with schema
  • Attach to slot service create/update/delete transitions
  • Add supplier setting to opt in/out
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • transactional rollback (no dispatch), receiver 4xx (do not retry), receiver 5xx (retry per policy)
• Include test output and notes

Example commit message

feat: slot.changed webhook

Guidelines

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

[MoscowDev]

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

I'd be happy to take this issue on. I have experience building production-ready applications and collaborating effectively through GitHub workflows, including implementing features, resolving bugs, and submitting well-documented pull requests.

I'll carefully review the existing implementation, identify the root cause, and deliver a robust, maintainable solution that aligns with the project's architecture and coding standards. Before submitting my PR, I'll thoroughly test the changes to ensure reliability and avoid regressions.

My goal is to contribute high-quality, clean, and maintainable code while communicating clearly throughout the process and delivering a dependable solution in a timely manner.

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

[khanavi272-spec]

@khanavi272-spec has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @khanavi272-spec to this issue.

[mikewheeleer]

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

I would like to work on this issue, and I have good knowledge of smart contacts and Sorabani Rust. Kindly assign it to me.

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

[drips-wave]

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

🧑‍💻 @MoscowDev: 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 @MoscowDev 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.