Version 0.1.6 release

Highlights

• open-data-products generate --provider claude now works without passing
  --config; it resolves to the Anthropic Messages API client.
• Config-free provider overrides now also work for openrouter, groq,
  lmstudio, and vllm, matching the bundled generation config defaults.
• Built-in provider defaults include provider type, model, base URL, and API
  key environment variable where needed.