UG-SIDHARTH/Mystery-box ? reverse-engineered prompt

Build me a simple event voting app where people can join with a QR code, upload one image, then rate posters from 1 to 5 stars and see the live leaderboard update right away. I want a participant page and a host dashboard, with the host able to generate invite links, move the event through waiting, upload, voting, and results, and reset everything when needed.

Make it work with FastAPI on the backend, SQLite by default, and a clean front end with vanilla JavaScript and Tailwind style. Please include image upload handling with validation and compression, real time updates so votes show instantly without refreshing, dark mode, CSV export for votes, and a way to download all uploaded images. If it helps, look up current docs online for any API details you need.