NAGESHJAGTAP/coupon_swap ? reverse-engineered prompt

Build me a full stack app called CouponSwap where people can securely buy, sell, and trade digital coupons. I want a clean, modern website with a good mobile friendly design, a landing page, sign up and login, a user dashboard, profile settings, a page to browse coupons, a page to sell coupons, and a success or verification flow after actions. Use real time updates and notifications so users can see new coupon activity instantly. Add email verification and basic email alerts too. Please make the authentication secure, with hashed passwords and token based login, and store everything in MongoDB.

Also include a simple Chrome extension version that lets users quickly access coupons and get notifications. The UI should feel polished and responsive, with smooth animations and clear icons for payment options like UPI, Paytm, Google Pay, and PhonePe. If you need to check current setup details, look up the latest docs online and then build the project so the frontend, backend, and extension all work together.