Contract: Add contract-level invariants for total supply and share-price consistency

[Junirezz]

Summary

Ensure the protocol always preserves mathematically valid vault state.

Problem

Invariants are not always checked when vault state changes.

Acceptance Criteria

• Assert total-supply and share-price invariants across transitions
• Add regression tests for violations
• Fail with clear errors when assumptions are broken
• Document key invariants for future contract changes

[SupremeCarMart100]

@SupremeCarMart100 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer,

I’d love the opportunity to work on this issue. I would greatly appreciate it if you could assign it to me.

Thank you for your consideration. I look forward to contributing to the project.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @SupremeCarMart100 to this issue.

[Escelit]

@Escelit has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I’d like to work on this issue because it addresses an important area of the project and presents a great opportunity to make a meaningful contribution. I’m particularly interested in delivering a solution that is reliable, maintainable, and aligned with the project’s existing architecture and development standards.

I have experience working across software development, including backend and frontend development, APIs, databases, testing, DevOps, and blockchain-based applications. I’m comfortable understanding existing codebases, identifying the root cause of issues, implementing clean and scalable solutions, and writing thorough tests to prevent regressions.

My approach would be to first understand the existing implementation and project conventions, then develop the solution in a focused and incremental way. I’ll ensure the changes are well-tested, documented where necessary, and do not introduce unnecessary complexity or break existing functionality. I’m also committed to clear communication, responding to review feedback, and delivering a polished contribution that provides real value to the project.

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

[AGWAM001]

@AGWAM001 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I'd love to take this issue on. I'm a full-stack developer with experience across Drips Waves4-7.
My stack include rust, Soroban, Solidity, and TypeScript. I can deliver a clean, tested, and well-documented solution within 24 hours of assignment.
Jovial to start immediately

ℹ️ Repo Maintainers: To accept this application, review their application or assign @AGWAM001 to this issue.