Build a native mobile app focused on real-time text-based chat between friends. The app should include the following screens and features: 1. **Authentication:** * A simple user signup and login system using a unique username and password. 2. **Contacts Screen:** * A screen that displays a list of the user's contacts or friends. * A feature to add new contacts by searching for their username. * Tapping on a contact's name should navigate the user to the chat screen with that person. 3. **Conversations List Screen:** * This will be the main screen after login. * It should display a list of all active conversations. * Each item in the list should show the friend's name, the last message sent in the conversation, and the time of the last message. * Unread messages should be clearly indicated (e.g., with a bold font or a dot). 4. **Chat Screen:** * This screen is for a one-on-one conversation with a friend. * It should display the message history with that friend, with the user's messages on one side (e.g., right) and the friend's messages on the other (e.g., left). * A text input field at the bottom for typing new messages. * A "Send" button to send the message. * Messages should appear in the chat view in real-time for both users.

Build a native mobile app focused on real-time text-based chat between friends. The app should include the following screens and features: 1. **Authentication:** * A simple user signup and lo...