Add regression test for sell quote after fee config update

[Chucks1093]

Summary
Add regression test for sell quote after fee config update

Scope

• add regression test for sell quote correctness after fee config mutation\n- verify output consistency with updated config\n- assert no stale-config reads

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

[Benedict315]

@Benedict315 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hello I would like to work on this as well

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Benedict315 to this issue.

[mofejo1]

@mofejo1 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Can you please assign this issue to me? I would like to work on this because I have experience writing contract tests and can implement a regression test that verifies sell quote correctness after fee config mutation, with assertions confirming output consistency and no stale-config reads.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mofejo1 to this issue.

[drips-wave]

Congratulations, @mofejo1! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @mofejo1: 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 🌊

[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @mofejo1 as part of the Stellar Wave Program's 4th Wave 🥳

Moderator's reason: [Auto-assessed] The contributor successfully implemented the requested regression test in PR #228, which verifies that sell quotes reflect fee configuration updates immediately and do not return stale data. The test logic and the accompanying snapshot file directly address the acceptance criteria defined in issue #220.

😎 @mofejo1: You earned 100 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.

ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.