gpt-image-* models return b64_json by default and reject the
response_format parameter with a 400 error. Only pass it for
DALL-E models which default to url.
- Add openai_text.py: text generation via OpenAI chat completions API
(gpt-4o, gpt-4o-mini, gpt-4.1, gpt-4.1-mini, gpt-4.1-nano, o3-mini)
- Add openai_image.py: image generation via OpenAI images API
(gpt-image-1 with reference image support, dall-e-3, dall-e-2)
- Refactor builder provider dispatch from TargetType to model-name index
to support multiple providers per target type
- Fix circular import between config.py and providers/__init__.py
using TYPE_CHECKING guard
- Fix stale default model assertions in tests
- Add openai>=1.0.0 dependency
