Add fractional-share supply-cap rounding boundary tests to prevent one-wei over-issuance

[greatest0fallt1me]

Description

Rounding during fractional-share issuance must never push the total one wei over the supply cap. Add boundary tests exercising every rounding mode at the near-cap edge.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/normalize_share_tests.rs, src/test_compute_share_invariants.rs
• Tests must cover RoundHalfUp, RoundHalfDown, RoundDown, RoundUp

Suggested execution

• Fork the repo and create a branch
• git checkout -b test/supply-cap-rounding-boundary
• Implement changes
  • Fixture total_issued at cap - 1
  • Issue amounts producing fractional shares
  • Assert final total never exceeds cap
• Validate security and correctness assumptions

Test and commit

• Run tests
  • cargo test --all
• Cover edge cases
  • Rounding mode causing an off-by-one push over cap
• Include test output and security notes

Example commit message

test: bound fractional supply-cap rounding

Guidelines

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

[devv-leo]

@devv-leo has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I’ll get this resolved in 24 hours if assigned to me.

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[drips-wave]

Congratulations, @devv-leo! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @devv-leo: 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.

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[drips-wave]

Congratulations, @devv-leo! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @devv-leo: 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 🌊

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@devv-leo's PR #706 was approved and merged by @thlpkee20-wq.

🏆 @devv-leo: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (293 total points). Track your full progress on GrantFox.

👏 Great work, @devv-leo! Keep contributing to RevoraOrg.