Allain-afk/Heyzine ? reverse-engineered prompt

Build me a modern flipbook web app where someone can upload a PDF and instantly view it as a smooth page turning book.

I want drag and drop upload, a nice viewer with realistic page flip animations, zoom and pan, fullscreen, dark mode, and easy navigation with buttons, arrow keys, and swipe on mobile. It should let me convert the PDF into shareable pages on the server, then generate a link I can send to other people. I also want public and private sharing options, so some files can be open to anyone and others stay restricted.

Please include support for rotating pages and adding video or audio overlays on specific pages. Make it feel polished and responsive on desktop and mobile, with preloading so page changes stay fast. If anything is unclear, look up the current docs online and use sensible defaults.