Add a native “Restart ComfyUI” button to the frontend

### What problem are you experiencing?

ComfyUI frequently requires a full backend restart after installing, updating, or developing custom nodes. At the moment, there is no clearly accessible native action in the frontend to restart ComfyUI.

This is especially inconvenient for custom-node developers, who may need to restart ComfyUI many times while testing Python changes, dependencies, routes, or frontend integrations. A browser refresh is not sufficient in these cases.

### When does this problem occur?

- Every single time a ComfyUI frontend restart is required

### How often do you encounter this problem?

Multiple times per day

### How much does this problem affect your workflow?

Causes moderate inconvenience

### Current workarounds

_No response_

### Ideas for solutions (Optional)

Please add a native **Restart ComfyUI** action somewhere easily accessible, for example:

- In the main application menu
- In the server/terminal panel
- Under Settings or Help
- Next to other server-management actions

The action should:

1. Ask for confirmation before restarting.
2. Warn the user if prompts are currently queued or running.
3. Trigger a full backend restart—not merely reload the browser.
4. Display a reconnecting screen and automatically restore the frontend connection when ComfyUI is available again.
5. Only be displayed or enabled when the current installation/runtime supports programmatic restarts.

For remote, cloud, containerized, or manually launched instances where the frontend cannot safely restart the process, the backend could advertise whether this capability is available.

### Additional context

Restarting is a normal and very frequent part of the custom-node development cycle. Making it a first-class frontend action would remove considerable friction and avoid repeatedly switching to a terminal or closing and reopening launch scripts.

I maintain several ComfyUI extensions, so this comes directly from repeated development experience:

- [OpenPose Studio](https://github.com/andreszs/ComfyUI-OpenPose-Studio) — visual OpenPose creation and editing
- [Styler Pipeline](https://github.com/andreszs/ComfyUI-Styler-Pipeline) — style suggestions and conditioning tools
- [LoRA Pipeline](https://github.com/andreszs/ComfyUI-LoRA-Pipeline) — area conditioning and LoRA scheduling

During development and testing of these plugins, I need to perform full ComfyUI restarts very frequently. A native restart button would make this workflow substantially faster and more convenient for extension developers—and would also help regular users after installing or updating custom nodes.

Thank you for considering it.

Start by locating the frontend application-menu or server-management entry points and the backend mechanism for advertising restart support. Trace how queued or running prompts, reconnecting UI state, and unsupported runtimes are represented; done means confirmation, appropriate warnings, a full restart, automatic reconnection, and hiding or disabling the action when unsupported.

Written by the indexing model from the issue text.