This commit adds:
- New test folder tests/responses_api_tests_proxy/ with Ruby SDK tests
- config.yaml with anthropic/* and openai/* wildcards
- Ruby spec file testing the Responses API with Anthropic model
- Validates output_tokens_details is properly set (not null) for Ruby SDK compatibility
- Tests basic, streaming, and tool call scenarios
- New CircleCI job e2e_ruby_sdk_responses_api to run the tests
This ensures the fix for output_tokens_details (reasoning_tokens default to 0)
is working correctly with the Ruby OpenAI SDK.
Co-authored-by: ishaan <ishaan@berri.ai>