Invoice ratings vector limits and abuse prevention

[Baskarayelu]

Description

Cap ratings count, validate score bounds, and prevent unbounded storage growth.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Align with existing Soroban contract patterns in quicklendx-contracts

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/invoice-ratings-limits
• Implement changes
• Write contract: src/invoice.rs
• Write comprehensive tests: src/test_invoice.rs, src/test_string_limits.rs
• Add documentation: docs/contracts/invoice.md
• Include NatSpec-style comments (Rust doc comments on public items)
• Validate security assumptions

Test and commit

• Run tests
• Cover edge cases
• Include test output and security notes

Example commit message

feat: add invoice ratings limits and validation

Guidelines

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

[drips-wave]

Congratulations, @EmmyKay0026! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @EmmyKay0026: 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.

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