Release v0.2.7

fix: correct settings attribute names for consistency (v0.2.7)

- Fix settings.vllm_openai_base_url -> settings.VLLM_OPENAI_BASE_URL
- Fix settings.openai_api_key -> settings.OPENAI_API_KEY
- Add missing WEAVIATE_URL and WEAVIATE_API_KEY to config
- Ensure all settings references use correct uppercase naming
- Bump version to 0.2.7