ci: add GitHub Action to check code formatting with Prettier

[vansh2408]

Pull Request Title Convention

Added a GitHub Actions workflow to automatically check all JavaScript (.js) and CSS (.css) files for proper formatting using Prettier.

• [CI/CD]: Add code formatting check with Prettier

🎯 What issue does this address?

Closes #12

✨ What does this change?

• Initialized package.json for project-level dependency management.
• Installed Prettier as a dev dependency.
• Added a format:check npm script to validate code formatting.
• Created .github/workflows/formatting.yml to automate Prettier checks on every push and pull request.

Checklist:

• New functionality meets the goals defined in the linked issue.
• If changing the UI or game experience, screenshots or a GIF are included below.
• Code is formatted cleanly (ran Prettier/ESLint locally).
• All CI/CD checks in this PR passed.
• Game mechanics work correctly (blocks stack, physics behave properly).
• Performance is maintained (no frame drops or lag introduced).
• Mobile/touch controls still function properly.
• Game resets correctly with 'R' key.

[vercel]

@vansh2408 is attempting to deploy a commit to the Maitri Vaghasiya's projects Team on Vercel.

A member of the Team first needs to authorize it.

[maitri-vv]

@vansh2408 Thanks for the efforts but its failing

I anyways dont want dependencies to get involved so i m closing the issue permanently, if u wish u can work on some other issues