dankbar-widgets-runningapps-groupbyapp

### Feature Description

dankbar-widgets-runningapps-groupbyapp

When you select this option, it groups by app. But when clicking on the group, it should open up a menu showing all the windows within that group to easily switch between them. I think people who use this widget are expecting that type of behavior. At least I am.

### Use Case

_No response_

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_

Start by locating the running-apps widget and the group-by-app selection handling; the issue names no files or tests. Done means clicking an app group opens a menu listing its windows, allowing users to switch between them across all compositors.

Written by the indexing model from the issue text.