ci: add prettier check workflow

[Gagan202005]

✅ Summary

This PR adds a GitHub Actions workflow to run Prettier formatting checks on pull requests to ensure consistent code style.

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🔧 Changes Included

• Added Prettier Check workflow
• Added format:check script:
  • prettier --check .
• Configured workflow to check only changed files in the PR (to avoid failing due to existing formatting issues in the repo)

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✅ Why this change?

• Ensures consistent formatting for new changes
• Prevents formatting issues from entering the codebase
• Keeps PRs clean without forcing a full repo reformat

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🧪 Testing Done

• npm run format:check
• Workflow runs successfully on PR

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