fix: resolve canvas error in game modals

[Bhavikapatel06]

📝 Description

Fixed the global canvas initialization issue causing multiple game modals such as Whack-a-Mole and Word Scramble to fail.

Added proper canvas existence checks in hero-canvas.js to prevent getContext null errors and improve game modal stability.

🔗 Linked Issue

Closes #456

---

📋 Contribution Checklist

• My code strictly adheres to the project guidelines (Standard library only, procedural code, clean spacing).
• I have verified that my files are placed in the correct directory.
• I have tested my changes thoroughly on my local machine.
• I have included interactive emojis and clean console/UI outputs.
• GSSoC 2026: I have been formally assigned to this issue and noted it above.

[vercel]

@Bhavikapatel06 is attempting to deploy a commit to the Anuj's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Bhavikapatel06]

Hi, I tried to deploy the project on Vercel, but it says authorization is required for deployment to the team project. Could you please check and approve/authorize it?

[github-actions]

🎉 Thank you for your contribution!

Your Pull Request has been merged successfully.

We appreciate the time and effort you put into improving this project. Contributions like yours help the repository grow and stay useful for everyone.

If you'd like to contribute again, please check the open issues and make sure you are assigned before opening another Pull Request.

Thanks again for your support! 🙌