I want to build LinguaFlow, a voice-first language practice app where learners talk with an AI coach through a clean, chat-style screen. Users should press-and-hold to speak, see a subtle “thinking” animation while the AI processes, then read the AI’s response and keep the conversation going. The app should remember past sessions and basic performance stats, and let users choose their target language and theme. It must run smoothly on phones and tablets from 4" to 12.9", including popular Chinese brands (Xiaomi, Oppo, Vivo, Huawei, Honor), and support UI localization and learning content for id-ID and pt-BR. Technically, build it in Kotlin with an MVI presentation layer; Jetpack Compose for the entire UI (using ConstraintLayout for robust layouts) and Material 3 with gentle motion; Hilt for dependency injection; Retrofit to call a backend for speech-to-text and NLP; Lottie for the “thinking” indicator; MMKV for conversation history and metrics; SharedPreferences for user settings; and expose ViewModel state via LiveData. Target Android 14+ devices (minSdk 33, targetSdk 35).