can i add image generation model configs for nano banana ?

### What would you like to be added?

Went through the repo and found that there is no image generation models like nano banana in the model configs. Shall I add it ?

Thankyou.

### Why is this needed?

Image generation is widely used everywhere, and accessing it via cli is equally important.

### Additional context

_No response_

No file or test is named in the issue. Start by locating the model-config implementation and the CLI path for image generation, then confirm whether Nano Banana is supported and what configuration is required. Done means an agreed configuration change is implemented and covered by the relevant checks.

Written by the indexing model from the issue text.