Devildonia/HadOS ? reverse-engineered prompt

Build me a browser based desktop OS called HadOS, with a real start menu, taskbar, draggable windows, a file manager, settings, and a few built in apps so it feels like an actual computer rather than a demo.

I want apps to run in isolated sandboxes so one frozen app can’t lock up the whole desktop, and I want the system to manage permissions before anything can access files, media, or other sensitive features. Please make it work offline as a PWA too, with local storage for files and app state.

Include the fun parts from the screenshots and README, like a 3D physics desktop pet, a couple of media and chat style apps, and a theme that looks polished and custom rather than generic. If there’s any AI related feature, keep it on device and clearly ask for consent before using it. Look up current docs online if you need to, and make sure the whole thing is testable and stable.