I’m building a lightweight age-calculator app exclusively for Android. The core requirement is that once the user enters their birth date, the app keeps updating their exact age in real time—years, months, days, down to seconds—without needing to tap any refresh button. Please handle the full development cycle: clean UI/UX, accurate time calculations that respect leap years and time zones, and smooth performance on recent Android versions. If you feel an optional birthday picker or even fun add-ons like zodiac info would improve usability, let me know, but the live age updates are non-negotiable. Deliverable: a fully functional APK plus readable, well-commented source code (Kotlin or Java) ready for submission to the Play Store.