feat(contracts): expose a typed event schema version helper

[enliven17]

Goal

Expose a typed helper reporting the event schema version expected by indexers.

Scope

Define one canonical version helper, leave event payloads unchanged, reject unsupported major versions, and document downstream use.

Acceptance criteria

• The value is deterministic and documented.
• Existing event names and field order remain unchanged.
• Unsupported major versions are rejected.
• Focused tests and documentation are included.

Test expectations

Use local fixtures only.

[enliven17]

Maintainer note: Please review the scope and acceptance criteria before applying. In your application, describe your implementation plan, the files or components you expect to change, and how you will test the result. Keep the contribution within the stated scope and include focused tests.

[Silver36-ship-it]

@Silver36-ship-it has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would love to work on this professionally, please assign it to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Silver36-ship-it to this issue.

[enliven17]

Thanks for applying. We reviewed the current application and assigned this issue to @Silver36-ship-it because it is currently the only Wave application. Please keep the event-version helper typed, deterministic, and limited to fixture tooling and documentation.

[drips-wave]

Congratulations, @Silver36-ship-it! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @Silver36-ship-it: 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 🌊