st9318469-ctrl/to-do-mern- ? reverse-engineered prompt

Build me a simple to do app with a frontend and a backend, using the existing project structure.

I want users to be able to add tasks, mark them as done, edit them, and delete them. Make it feel clean and easy to use, with a basic modern interface on the front end and a small API on the back end that saves the tasks properly instead of just keeping them in memory.

Set it up so I can run the app locally and use it right away. If anything in the current setup looks incomplete, please fill in the missing pieces and wire everything together so the frontend talks to the backend correctly. Keep the code straightforward and organized, and if you need to check current docs for anything, go ahead and look them up online.