Improve contributor onboarding documentation

[Nanle-code]

Summary:
New contributors need a more precise, practical guide to building, testing, and contributing to the project.

Why this matters:
A better onboarding flow lowers the barrier to entry and increases the likelihood of sustainable community contributions.

Proposed work:

• Create a concise contributor quickstart
• Document how to set up Rust, run tests, and reproduce common issues
• Add a pull request checklist for contributors

Acceptance criteria:

• New contributors can follow the guide without guesswork
• The guide includes build and test instructions
• The expected contribution process is documented clearly

[frank0277]

@frank0277 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @frank0277 to this issue.

[nonso7]

@nonso7 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Can i work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @nonso7 to this issue.

[drips-wave]

Congratulations, @nonso7! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @nonso7: 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 🌊