Add currency normalization validation for bill totals

[Baskarayelu]

Description

Add normalization and validation in currency-based bill queries so totals remain consistent for equivalent currency codes.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Handle case sensitivity and invalid currency symbols safely

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/bills-currency-normalization
• Implement changes
• Write contract: bill_payments/src/lib.rs
• Write comprehensive tests: bill_payments/src/test.rs
• Add documentation: bill_payments/README.md
• Include NatSpec-style comments
• Validate security assumptions

Test and commit

• Run tests: cargo test -p bill_payments
• Cover edge cases
• Include test output and security notes

Example commit message

feat: normalize currency handling in bill totals

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[drips-wave]

This issue has been added to the Stellar Wave Program and is worth 200 Points.

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[vrickish]

@vrickish has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

hi, maintainer. I have experience building secure financial systems and handling currency validation, so I know how to keep totals consistent while managing edge cases like case sensitivity. I can deliver the required 95 percent test coverage and clear documentation within the 96 hour timeframe.

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

[drips-wave]

Congratulations, @vrickish! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @vrickish: 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.

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