Please Add a Confirmation Prompt When Closing an Instance in ComfyUI Manager

### Feature Idea

I'm using the ComfyUI Desktop version.

When I'm generating a video on a selected instance, if I accidentally click the close button, the instance shuts down immediately.

Could you please add a confirmation prompt asking, "Are you sure you want to close this instance?" before shutting it down?

Alternatively, it would be great to have an option in the settings to enable or disable this confirmation prompt.

It's really heartbreaking when a video has been generating for a long time and the instance gets closed by accident with only a few minutes left. 😭

### Existing Solutions

_No response_

### Other

_No response_

Start by locating the ComfyUI Desktop entry point that handles the instance close button; the issue names no file or test. Confirm the prompt appears before shutdown, preserves the instance when canceled, and covers the requested close action; clarify whether the optional settings toggle is part of the work.

Written by the indexing model from the issue text.