Wallpaper switching does not work with multiple desktops

### Description

Theme switching does not work with multiple desktops.

For taskbar, start menu, and stuff, the app is working to automatically switch dark and light themes.
However, for the wallpaper, the app switching does not work, only the first virtual desktops among many desktops get switched to the correct wallpaper.

Manual switching with shortcut keys still works and could switch the current desktop to the correct theme.
However, the other desktops are still left behind with the old wallpaper from the other themes.

### Expected Behavior

ADM should be able to switch all desktop wallpapers together.

I guess this could be done with a for-loop, where the AMD switches all desktops sequentially.

### Log Data

[service.log](https://github.com/AutoDarkMode/Windows-Auto-Night-Mode/files/8910797/service.log)
[config.yaml.log](https://github.com/AutoDarkMode/Windows-Auto-Night-Mode/files/8910820/config.yaml.log)

### Operating System

Windows 11 pro 1000.22000.739.0

### Commit Hash and Version

- Commit: `5e6ea8a`
- Service: `10.1.0.10`
- Updater: `2.4.2`
- App: `10.0.1.0`
- Shell: `1.3.1.0`
- .Net: `6.0.0`

### Screenshots

Reproduce the issue on Windows 11 with multiple virtual desktops, automatic theme switching, and different wallpapers; use the attached service.log and config.yaml.log as context. Trace the wallpaper-switching entry point and determine why only the first desktop is updated. Done means an automatic theme change updates every virtual desktop while preserving the working manual shortcut behavior.

Written by the indexing model from the issue text.