I need a web-based quiz application built specifically for educational use. It should let me create and deliver both Multiple choice questions and Open-ended questions, then grade or store the responses automatically. Each quiz will run on a countdown clock, closing itself when time expires, and a real-time Leaderboard must update as soon as attempts are submitted so students can see where they stand. A clean admin panel where I can add, edit, or archive questions and set the quiz duration is essential. Students will log in securely, take the quiz on desktop or mobile, and receive instant feedback once they finish. Clear, well-structured code and straightforward deployment instructions are part of the deliverable so I can maintain the app long term. Please build it with a modern, widely supported tech stack—feel free to suggest what you think is best—and keep usability and performance in mind from the start.