Add a reporter that posts the RepoBench leaderboard back to a pull request or issue.\n\nAcceptance criteria:\n- New CLI option for GitHub Markdown output suitable for PR comments.\n- GitHub Action example that comments on a PR with the summary table.\n- Include links to artifacts when available in Actions.\n- Keep local CLI behavior unchanged by default.
Add a reporter that posts the RepoBench leaderboard back to a pull request or issue.\n\nAcceptance criteria:\n- New CLI option for GitHub Markdown output suitable for PR comments.\n- GitHub Action example that comments on a PR with the summary table.\n- Include links to artifacts when available in Actions.\n- Keep local CLI behavior unchanged by default.