I want a simple, reliable Android application whose main job is to process in-app purchases. The user journey can stay lean—no account creation, social sign-ins, or push notifications for now—just a clean interface that leads to Google Play Billing and confirms the transaction. You are free to choose Kotlin, Java, Flutter, or React Native as long as the final build installs smoothly on current Android versions and passes Google Play’s billing tests. A minimalist UI that clearly shows the purchasable item, handles error states, and reports a successful purchase is all I need. Deliverables • Clean, well-commented source code • Release-ready APK signed and aligned for Play Store upload • Short README: how to change product IDs, test purchases, and generate future builds