feat: Implement account sequence manager

[cypriannwokolo2-creator]

Description

Prevent sequence number gaps with a thread-safe sequence manager that refreshes from chain when stale.

Requirements

• Implement AccountManager with mutex
• Add sequence number tracking
• Add chain refresh when stale (30s max drift)
• Add reset function for external transactions

Acceptance Criteria

• Sequence numbers never gap
• Thread-safe with mutex
• Refreshes from chain when stale
• Handles external transactions

Priority

High

[graceanya796-maker]

@graceanya796-maker has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello
I would love to work on this issue please

ℹ️ Repo Maintainers: To accept this application, review their application or assign @graceanya796-maker to this issue.

[rilwanubala]

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

Hi, Please allow me to work on this issue

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

[bobaivigitalpoint-ui]

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

Hello, I'm interested in taking this issue on.

I have hands-on experience with backend development, databases, and API design, as well as frontend work with React and modern CSS. I write tested, maintainable code and enjoy contributing to open source projects.

I've gone through the details of this issue and I'm confident I can deliver a clean, well-tested solution that fits the codebase.

Looking forward to contributing — please assign this issue to me.

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

[linesofcodes0-cloud]

@linesofcodes0-cloud has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I'm a full-stack developer and I'd like to take this issue.
I understand the requirements and will follow the existing project structure, keep the implementation clean, and include proper tests where applicable.

ETA: 1–3 days (depending on scope)

ℹ️ Repo Maintainers: To accept this application, review their application or assign @linesofcodes0-cloud to this issue.

[drips-wave]

Congratulations, @bobaivigitalpoint-ui! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @bobaivigitalpoint-ui: 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 🌊