Improve CLI error messages and recovery guidance

[Nanle-code]

Summary:
Several error paths in the CLI are too generic or incomplete. Contributors and users would benefit from more actionable messaging.

Why this matters:
Clear error messages reduce frustration and help users resolve issues quickly without relying on the maintainer team.

Proposed work:

• Standardize error formatting across commands
• Add practical next steps for common failures
• Improve validation messages before actions are executed

Acceptance criteria:

• Errors include clear context and suggested actions
• Users can identify what went wrong without guesswork
• Common failure cases are documented in output

[Jonathan-ai9]

@Jonathan-ai9 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi,I’d like to work on this issue. I will improve CLI error handling by standardizing error messages, adding actionable recovery guidance, and enhancing validation feedback so users can quickly understand and resolve common issues.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Jonathan-ai9 to this issue.

[drips-wave]

Congratulations, @Jonathan-ai9! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Jonathan-ai9: 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 🌊