Ranchero-Software/NetNewsWire ? reverse-engineered prompt

Build me a free and open source RSS reader app for iPhone, iPad, and Mac that feels polished and simple to use.

It should let people add feeds, browse unread and starred items, read articles in a clean reader view, and support RSS, Atom, JSON Feed, and RSS in JSON. I want it to feel like a real native Apple app, with a smooth sidebar, nice typography, dark mode, and a focused reading experience. Make sure it works on both macOS and iOS, and keep the codebase organized so the shared logic is reused where it makes sense.

If you need to look up current Apple docs or best practices while building it, go ahead. Also include a basic way to run and test it locally, and make sure the project can build without requiring anything weird from the user.