[Contracts] Implement Owner-Guarded Circuit Breaker (Pause/Unpause)

[ONEONUORA]

Description

Add pausing capabilities for security/emergency events:

• Guard functions with a global status check (is_paused).
• Admin functions to set status.

Acceptance Criteria

• Prevents creating/claiming plans when paused.
• Standard queries (like get_plan) remain functional while paused.
• State changes logged via events.

[abdullahi503-lab]

@abdullahi503-lab has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @abdullahi503-lab to this issue.

[drips-wave]

Congratulations, @abdullahi503-lab! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @abdullahi503-lab: 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 🌊