Responsive Revenue-Split E-Commerce Site

I need a fully responsive e-commerce site that works like an online mall, where every sale automatically sends 20 % of the payment to me and the remaining 80 % to the supermarket or store that listed the product. The split has to be executed through MPesa, so the build must talk directly to the MPesa API and log each payout clearly for both parties.

Please structure the store catalogue, cart, secure checkout, and order-tracking flow, then add an admin area where I can:
• onboard new stores,
• change the commission rate when needed, and
• view live sales and payout reports.

The front end must be mobile-first, fast, and SEO-friendly. Once finished, install everything on my hosting account and walk me through a test transaction so I can see funds divide 20 / 80 in real time and both dashboards update instantly.