I need a straightforward text-only chat module for an existing mobile app (both iOS and Android). The goal is to let users message one-to-one in real time after they verify their phone number. Scope & key points • Build the chat service end-to-end: database, real-time messaging layer, and clean API endpoints my app team can call. • Integrate phone number verification as the sole sign-in method; once verified, users are automatically logged in. • Deliver lightweight, well-commented sample screens in React Native or Flutter—whichever you prefer—showing login, contact list, and chat room. • Messages should appear instantly, handle offline/online status gracefully, and sync when the device reconnects. • Provide clear setup docs and a short hand-off call so my team can plug the module into our codebase without friction. I’m open to your preferred stack—Firebase, Supabase, or a custom Node.js + WebSocket solution—as long as it stays reliable and easy to maintain. Let me know which you’d use, how quickly you can deliver a working build, and any prior chat applications you’ve shipped.