AkkhileshCod3s/dropportal ? reverse-engineered prompt

Build me a simple file sharing web app called DropPortal.

I want users to be able to upload a file, then get a shareable download link right away. It should also show a QR code for that link so someone can scan it on their phone and open the download page quickly. Keep the interface clean, modern, and responsive so it works well on desktop and mobile. Make the upload experience feel easy, with drag and drop if possible, plus a normal browse button too.

Use Flask for the backend and keep the frontend lightweight with plain HTML, CSS, and JavaScript. I want it to feel fast and straightforward, not bloated. Set it up so I can run it locally with a simple Python command, and make sure the app works nicely for a small public deployment too. If anything is unclear, look up current docs online if you need to.