I want to build an online crypto casino website that can handle tens of thousands of users concurrently. I want the backend built with either Node.js or Java Spring and the database built with either MySQL or PostgreSQL. The website must have both cryptocurrency payment gateways and fiat payment gateways and KYC requirements ONLY when withdrawing funds. The website should be clean, responsive, and fast with minimal, app-like interfaces that load quickly and work seamlessly across devices. The backend should handle game logic, user data, payment processing, and security. I want to use smart contracts but still need a robust backend to manage services like login sessions, analytics, KYC triggers, and real-time game tracking. I want AWS or Cloudflare for cloud services. I will be supplying my own games, and the website must run smoothly across all major screen sizes, browsers and mobile phones. Wallet connections and in-game currency conversion tools must be tested on mobile and desktop, since these features often behave differently than on desktop. Must be the same fast, smooth gameplay no matter what device is used and must have a dark, fast, reactive and smooth UI/UX which is attractive to players.