Pin Stellar/Soroban CLI version in CI and scripts

[devsimze]

Problem

CI installs soroban v21.2.0 while README references generic stellar-cli—version drift breaks builds.

Scope

• ci.yml, scripts/deploy-devnet.sh, README

Acceptance criteria

• Single version pin file (e.g. .stellar-version).
• All scripts source the same version.

[Okorie2000-code]

@Okorie2000-code has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Can I work on this?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Okorie2000-code to this issue.

[Menjay7]

@Menjay7 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi! I’m a full-stack developer with a strong blockchain background. I’d love to handle this issue and can deliver a clean, reliable solution. Kindly assign it to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Menjay7 to this issue.

[covenantalade]

@covenantalade has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Let me work on this

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

[drips-wave]

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

🧑‍💻 @covenantalade: 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 🌊