EIjazJalil313/chat_app ? reverse-engineered prompt

Build me a simple mobile chat app in React Native that feels clean and modern on both iPhone and Android.

I want a main chat screen with a list of messages, a text box at the bottom, and a send button so I can type and see messages appear in the conversation. Make it look polished, with a nice header, readable bubbles, good spacing, and support for both light styling and a dark feel if it fits the design. Keep it easy to run and easy to tweak later, since this is just the starting point for a chat app.

Please wire it up so it works smoothly in the existing project, and keep the code organized so I can build on it later. If you need to check current React Native docs or best practices, go ahead and look them up online.