gaball1/Duckie ? reverse-engineered prompt

Build me a cross platform language learning app called Duckie that helps students improve their English with lessons, quizzes, conversations, and progress tracking.

I want a polished Flutter app that works on mobile and desktop, with a clean onboarding flow, registration and login, a placement test for new users, and a dashboard that shows level, points, units, lessons, and progress. Users should be able to learn words, hear words, use words, take quizzes with instant feedback, practice real life situations, join guided conversations, chat with friends, coaches, and a Duckie AI helper, and earn achievements as they go.

Please also include an admin area for managing lessons, units, quizzes, and student progress, plus secure sign in, password reset by email, reminders, theme switching, membership status, and account deletion. Use the existing screenshots and README as the guide for the look and flow, and if anything is unclear, look up current docs online if needed.