feat: add GitHub API rate limit awareness

[Jiya3177]

Summary

Add rate-limit awareness to GitHubCLIProvider before GitHub API calls.

Related Issue

Fixes #37

Type of Change

• Bug fix
• New feature
• Documentation
• Refactoring
• Test changes
• CI/Chore

Testing

• uv run ruff check passes
• uv run mypy passes
• uv run pytest passes
• Manual testing done

Manual testing:

• PYTHONPATH=src python3 -m pytest tests/oss/test_github_cli_provider.py
• python3 -m ruff check src/oss_dev/providers/github/client.py tests/oss/test_github_cli_provider.py

Description

Added rate-limit checks before gh api calls in GitHubCLIProvider.

This change:

• Parses gh api rate_limit output.
• Blocks API calls when remaining quota is exhausted.
• Warns on low remaining quota.
• Handles malformed rate-limit responses gracefully.
• Handles rate-limit CLI errors with clearer ProviderError messages.
• Avoids recursive checks for gh api rate_limit.

Added focused tests with mocked subprocess.run so no real GitHub API calls are made.

[Hell1213]

@Jiya3177 Thanks for you contribution , I'm on it will review it shortly

[Hell1213]

Review: GitHub API rate limit awareness

Hi @Jiya3177, thanks for this PR! The rate limit awareness is well-implemented.

Verified: Tests pass (77/77), ruff checks clean.

Suggestion: _get_rate_limit() calls subprocess.run directly without checking if gh is available. If gh is not installed, the error message from subprocess wont be user-friendly. Consider adding self._require_gh() or self._check_gh() at the start of _get_rate_limit() to give a clear error message.

Important: PR #50 by @Achiever199 also modifies src/oss_dev/providers/github/client.py (adds caching layer). Both PRs touch _run_gh and the class methods. There will be merge conflicts – whoever merges second will need to rebase and reconcile changes to _run_gh, fetch_issue, list_issues, create_pr, etc.

[Hell1213]

Rate limit logic looks solid. The tests cover the key cases (zero quota, low quota, malformed response, no recursion on rate_limit endpoint). One small thing - _get_rate_limit() uses subprocess.run directly instead of going through _run_gh, so if gh is not installed the error wont be as clear. Not a blocker though.