Add unit tests for co-creator fee split summing correctly to full creator fee

[Chucks1093]

Summary

When a co-creator config is set, the co-creator share plus the creator fee recipient share must equal exactly the full creator fee with no XLM lost. A unit test should confirm this invariant holds across different split percentages.

Scope

• Register a creator with a co-creator at 30% share
• Execute a buy and record both the creator fee recipient and co-creator balance increases
• Assert their sum equals the total creator fee for the trade
• Repeat for a 50% and 10% split

Acceptance Criteria

• Co-creator amount plus creator recipient amount equals total creator fee
• No XLM lost in the split at 30%, 50%, and 10% share values
• Test fails if either party receives more than their share

ETA: 12 hours

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Coordinate on Telegram

[abioye-emma]

Hi, I’m a full-stack Web2 & Web3 developer with open-source contribution experience, and I’d be glad to work on this issue.

[Unclebaffa]

Hello Maintainer,
I'm interested in contributing to this amazing project of yours, I'm confident i will deliver the best result that aligns with this project.
Kindly assign me.
Thank you

[grantfox-oss]

🦊 GrantFox — @Unclebaffa has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #545)
2. Your PR will be reviewed by the accesslayerorg maintainers

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