chathushkaimasara/My-Workouts ? reverse-engineered prompt

Build me a clean, premium workout tracker app in Flutter for Android that works completely offline. I want it to feel minimal and distraction free, with a polished modern look, light and dark mode, and a nice custom theme that can match the device colors or use a few preset colors.

The app should let me plan workout days like Push, Pull, Legs, reorder my schedule, and add custom workout backgrounds if possible. I also want to log sets, reps, and warmups during a workout, with a simple way to mark things complete as I go.

Please include a progress screen that shows my personal records over time with charts, plus a local only data setup so nothing needs an account. If you can, add backup and restore through import and export so I can keep my data safe. Make the UI feel really smooth and premium, with small animations and a friendly first time welcome screen.