Anirudh-Negii/timestone ? reverse-engineered prompt

Build me a premium watch shopping site that feels polished and modern, with a strong focus on responsive design for both desktop and mobile. I want people to be able to browse different watch brands and collections, view product highlights, see limited time offers, read testimonials, and move through a smooth shopping flow from browsing to checkout.

The app should include simple signup and login using saved local data, with protected cart access so only signed in users can manage their cart. I need a global cart that can add items, update quantities, remove products, and show totals clearly across the app. Please include clean routing for the main pages, brand specific collection pages, cart, checkout, and a nice custom not found page. Use the existing React setup and make the UI feel high end, with watch focused visuals and easy navigation. If you need current guidance on anything, look up the latest docs online.