Multiplatform Chat & Call App

I need an application that runs smoothly on iOS, Android, and the web, sharing a single codebase. The first release must handle one-to-one text chat and in-app calling; group conversations can wait, so please structure the backend so that a switch can enable them later without refactoring.

Feel free to choose the stack you work fastest in—React Native, Flutter, or another cross-platform framework is fine—as long as the web build is equally performant. WebRTC, Twilio, or a comparable SDK can power the voice side; real-time messaging can sit on Firebase, Socket.IO, or a similarly reliable service.

Deliverables
• Source code for mobile and web builds
• Auth + real-time text chat + voice call working in all three environments
• Simple, clean UI/UX with basic user presence indicators
• Clear setup instructions and build scripts so I can deploy new versions myself

Code quality, stability, and ease of future expansion to group chat are my top priorities.