Add event test for sell payload fee fields

[Chucks1093]

Summary
Add event test for sell payload fee fields

Scope

• add event tests validating sell event fee-related payload fields\n- verify field presence and value mapping\n- keep test fixtures reusable

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

[rehna-jp]

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

Hii,

I’d like to add event tests for sell payload fee fields in accesslayer-contracts.

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

[drips-wave]

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

🧑‍💻 @aistitchpay-sys: 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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