Export an image

### User Story Description

As a user, I want to be able to export an image from the viewer.

### Acceptance Criteria

Start a VISOR session. Load a dataset. Use the API call to export an image. An image is generated on disk. Now, change the model visualization (parts visibility, mesh, color by variable, ....). Use the same API to export an image. The image shows the current state of VISOR.

### Additional Links

_No response_

### Requires new or update to third party ? If "yes" add the name(s) and the version(s) of the Third Party Software.

No

### Name and Version for Third Parties

_No response_

Start a VISOR session, load a dataset, and locate the existing API entry point used for viewer operations. Export an image before and after changing parts visibility, mesh, or color by variable; done means both images are written to disk and the second reflects the current visualization state.

索引モデルが issue の本文から書いたものです。