cashubtc/wallet ? reverse-engineered prompt

Build me a native Cashu wallet app for both iPhone and Android that lets people manage ecash, send and receive Lightning payments, handle on chain Bitcoin, pay from Nostr payment requests, and use NFC contactless payments.

I want the iPhone version to feel like a clean SwiftUI app and the Android version to feel like a modern Kotlin app with Jetpack Compose. Keep the experience simple and polished, with the main wallet screens, payment flow, balance view, transaction history, and basic settings. If you need to check current platform docs or best practices, look them up online.

Please make the project runnable on both platforms, with the iOS app building in Xcode and the Android app building with Gradle. Follow the existing product and design notes if they’re there, and keep the implementation aligned across both apps as much as possible.