Add creator list cursor checksum helper

[Chucks1093]

Summary
Add creator list cursor checksum helper

Scope

• add checksum helper for cursor integrity verification\n- apply helper in cursor generation/validation paths\n- return consistent error on checksum mismatch

Acceptance Criteria

• scoped change is implemented with no unrelated file churn
• docs/tests are updated where applicable
• contributor can validate the outcome locally

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg

[khanavi272-spec]

@khanavi272-spec has applied to work on this issue as part of the Stellar Wave Program's 4th 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.

[Kaycee276]

@Kaycee276 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi, I'd like to take this on! I'll add a scoped checksum helper (likely HMAC-based) for cursor integrity, wire it into the creator list cursor generation and validation paths, and return a consistent error on mismatch — no unrelated file churn. PR in 30 hours, and I'll reach out on Telegram now.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Kaycee276 to this issue.

[drips-wave]

Congratulations, @Kaycee276! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @Kaycee276: 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

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[drips-wave]

This issue has been completed by @Kaycee276 as part of the Stellar Wave Program's 4th Wave 🥳

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