UG-SIDHARTH/OMNI-PDF ? reverse-engineered prompt

Build me a clean web app that lets people upload a PDF or an image, then use a few simple tools on it and download the finished file.

I want the app to feel modern and easy, with drag and drop upload, clear actions for things like merging, splitting, and basic PDF editing, plus an image background remover that works in the browser. Make the interface smooth and polished, with nice animations and a mobile friendly layout. Use a React front end and a small Express server for handling uploads and file processing, and make sure uploaded files can be saved and downloaded properly.

Please also add sensible limits so the server does not get abused, and set it up so it can run locally in development and be easy to deploy with Docker. If you need to look up any current docs online, go ahead and do that.