fix AI-88
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Added support for the new image generation model "gpt-image-1" in both backend and frontend.
- Updated available prompt options to include "gpt-image-1" for image creation actions.
- **Improvements**
- Set a 5-minute timeout for image generation requests to improve reliability.
- **Tests**
- Expanded test coverage to validate image generation using the new "gpt-image-1" prompt.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Close [BS-2834](https://linear.app/affine-design/issue/BS-2834).
### What Changed?
- Change `reference_index` from chip order to increasing positive integer.
- Add matched context documents to ai prompt.
