Support netrc auth

Instead of having to pass a token manually over the CLI, it could automatically pick it up from the netrc file.

There is a nice octokit plugin for it already: https://www.npmjs.com/package/octokit-auth-netrc

So the order could be:

1. Manually passed token
2. Any token(s) from netrc file.
3. Anonymous auth.
4.

Start by reading the existing CLI token-handling entry point and the octokit-auth-netrc plugin documentation linked in the issue. Implement the documented precedence: manually passed token, netrc token(s), then anonymous authentication, and verify each fallback path with the project's existing checks.

Written by the indexing model from the issue text.