Add Emergency Pause Mechanism

[Mkalbani]

Description

There is currently no way to halt the contract in case of an exploit or vulnerability discovery.

Expected Behavior

The contract owner should be able to pause all quest creation and completions instantly.

Proposed Changes

• Integrate OpenZeppelin Pausable
• Add whenNotPaused modifier to createQuest() and completeQuest()

Acceptance Criteria

• Owner can pause and unpause the contract
• All state-changing functions respect the pause state
• Tests cover paused and unpaused scenarios

[Lynndabel]

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

Hello maintainer, i have gone through the task description and will like to work on this please. ETA: 6hours

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

[JoaquinSkorg]

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

Hello maintainer, kindly assign this issue to me. I've gone through the description and acceptance criteria and I'm confident I'll deliver in 2hrs max

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

[ayshadogo]

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

Hello Maintainer

I would like to work on this please

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

[nafiuishaaq]

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

Let me professionally implement this task as soon as possible

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

[drips-wave]

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

🧑‍💻 @nafiuishaaq: 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.

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