[macos] Add macOS binary build to GitHub Actions workflow #362

At the moment, our GitHub Actions workflow builds release binaries for Windows and Linux (Debian).
It might be worth considering extending the workflow to also produce binaries for macOS, to improve platform coverage and make it a lot easier for macOS users to run the project without building from source.

Code Signing / Security Notes

The macOS binaries would be self-signed (or unsigned from Apple's perspective), meaning they will not include an official Apple Developer ID signature.

Because of this:

• macOS Gatekeeper may block execution by default.
• Users will likely need to manually allow execution by adding an exception in:
• System Settings → Privacy & Security
• and using "Allow Anyway" for the downloaded binary.

This is expected behavior unless we decide to introduce proper Apple Developer signing/notarization in the future.