Windows Support with Wallpaper Sync across Devices

## **Is your feature request related to a problem? Please describe.**
There isn't a cross-platform wallpaper app that can sync the chosen wallpaper between platforms. This is a niche that is yet to be filled, and for those individuals who would like to maintain that consistent look across their PCs/Phones/Tablets, Prism could be the go-to app.

## **Describe the solution you'd like**
Flutter recently officially introduced support for Windows apps, and it would be nice to have Prism releases for the Microsoft Store too with the same features. Due to the cross-platform nature of Flutter, I believe this is a relatively easier task for Prism than other apps written in different languages/using other frameworks. The primary feature that could make Prism stand out here is the ability to keep the wallpapers synced between platforms. This way, when wallpaper is force changed/schedule changed on either platform, the changes reflect on all your devices using Prism, creating an even and consistent look and feel.

This syncing would also have to be handled via an account-based system, rather than a pairing via Bluetooth/WiFi-based system, cause an account-based system will remain much more reliable than a pairing based system, albeit at the cost of a minor sync delay across devices.

## **Describe alternatives you've considered**
There are no alternatives to this problem, that can be considered. The only apps that even come close to allowing this functionality are apps that are used as general bridges between PCs and mobile devices and those come with a lot of other cluttered features. There is no pure wallpaper app available that accomplishes this task.

The issue names no files, tests, or entry points; begin by mapping the existing Flutter Android/iOS wallpaper and scheduling flows. Then determine the scope for Windows support and account-based cross-device synchronization, with equivalent wallpaper behavior across supported platforms as the completion criteria.

Written by the indexing model from the issue text.