Screenly/Anthias ? reverse-engineered prompt

Build me an open source digital signage app for Raspberry Pi and regular PCs that lets me upload images and videos, organize them into a simple library, and schedule what plays on each screen throughout the day.

I want a clean web dashboard where I can add a device, choose a playlist or single asset, set a schedule, and see what is currently showing. It should be easy to install on Raspberry Pi OS, balenaOS, and other 64 bit Debian based ARM boards, and it should also work on desktop Linux machines. Make sure it can play content reliably in a browser style viewer, with the app taking over the screen and starting automatically after reboot.

Please include sensible defaults, a straightforward setup flow, and basic docs so someone with little technical experience can get it running. If you need to check anything, look up the current docs online first and then build it in a way that matches the project’s existing style.