Fix Next.js E-commerce Project + Build Backend

I recently obtained a public e-commerce project built with Next.js from GitHub. The project runs on my side, but several issues are currently preventing it from functioning properly. For example, the category section is not displaying correctly, product pages (PDP) are not opening when products are clicked, and there are multiple other bugs throughout the application. I am looking for an experienced full stack developer who can help me fix these issues, customize the UI to match my brand identity, and support me in launching the store successfully. At the moment, the project appears to include only the frontend, so I believe the backend will likely need to be built from scratch. For the backend stack, I am open to your recommendation. Please choose the framework and architecture you believe are the most suitable, modern, and scalable for this project. Experience with Next.js, e-commerce platforms, API development, authentication systems, payment integration, database architecture, and deployment is highly preferred. Budget: USD 30–250