Add two new image generation providers:
- `openai` — uses the standalone OpenAI Images API
(`/v1/images/generations`) with an API key. Supports DALL-E
and gpt-image-* models, with automatic parameter adjustment
(gpt-image models don't accept response_format or n).
- `openai_codex` — uses the Codex Responses API with the
`image_generation` tool, authenticated via OAuth subscription
token. The same mechanism ChatGPT uses internally.
Also remove the API key pre-check in ImageGenerationTool so
providers that handle their own auth fallback (like Codex OAuth)
can work without a configured key.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Adds GeminiImageGenerationClient covering both Imagen 4 (:predict) and
Gemini Flash (:generateContent), wires the gemini ProviderConfig through
the SDK, API server, and gateway entry points, and updates the
image-generation docs and skill. Errors from the Gemini endpoints are
logged and surface with the HTTP status and parsed message instead of an
empty string.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
