[Feature Request]: Auto-detect OAS breaking changes

[shgokita]

Summary

Add a GitHub Actions workflow to automatically check OpenAPI Specification changes in PRs and detect breaking changes to maintain API backward compatibility.

Background

Currently, multiple OpenAPI definition files (user, provider, admin, user_signup) exist, but there is no automated mechanism to check whether changes to these files break backward compatibility. Since breaking changes in APIs can impact existing clients, we need to be able to detect them at the PR stage.