fix: enable Prettier GitHub Action to auto-commit formatting changes

[vansh2408]

Summary

Fixes the Prettier GitHub Action to successfully commit and push formatting changes back to pull request branches.

Related Issue

Closes #151

Problem

The Prettier action was running successfully and detecting formatting issues, but failing to commit and push the fixes back to the PR branch. Changes remained local to the CI environment and were never persisted.

Solution

This PR implements several critical fixes:

Changes Made

• Added Explicit Permissions
  Added contents: write permission to allow pushing commits
  Added pull-requests: write permission for PR comments
• Fixed Branch Checkout
  Changed checkout ref to ${{ github.head_ref || github.ref }}
  Ensures we checkout the actual PR branch, not a merge commit
• Corrected Push Command
  Updated to git push origin HEAD:${{ github.head_ref || github.ref_name }}
  Explicitly targets the correct branch reference

Additional Notes

Fork PRs: Due to GitHub security restrictions, this action cannot automatically commit to PRs from forked repositories. For fork PRs, consider:

• Requesting contributors open PRs from branches in the main repo
• Adding a separate workflow that comments on fork PRs requesting manual formatting

[vercel]

@vansh2408 is attempting to deploy a commit to the idna001's projects Team on Vercel.

A member of the Team first needs to authorize it.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[idna001]

Hi, thanks for the PR. Right now, the Action fails on another step. It don't finds the PR.
What is it about?