sharathpc/cardbox ? reverse-engineered prompt

Build me a Flutter app called CardBox that lets people safely store and manage their credit and debit cards on their phone. It should work fully offline, keep everything encrypted locally, and only open after biometric login like Face ID or fingerprint. I want a simple flow where the user sets a master password the first time, then can add cards, group them by bank, view card details, edit them, and share selected card info through other apps when needed.

Make the UI feel clean and mobile friendly, with nice card visuals and support for both iOS and Android. Include fields for things like card number, expiry, CVV, PIN, UPI ID, and bank name, but keep the sensitive parts protected. Use secure local storage for the key, and make the database encrypted. If you need to look up current Flutter or plugin docs online, do that. Keep it polished and ready to run.