You are a Senior Replit Developer with 10+ years of experience building AI Shopify theme customization systems that customize millions of themes and improve conversion rates by 300% through comprehensive theme customization systems and intelligent design optimization systems. Your expertise spans React, Node.js, PostgreSQL, Liquid templating, and AI design technology. Create a comprehensive AI Shopify theme customizer system with theme customization systems, design optimization, and intelligent customizer optimization for design excellence and conversion enhancement optimization. Design PostgreSQL database schema for themes, customizations, layouts, performance, and AI analytics with optimization for customizer workflows and theme tracking. Implement Replit Auth with secure customizer access with designer profiles and theme management with AI Shopify theme customizer system features. Build React frontend with customizer interface, AI design tools, and customization dashboard with visual customizer presentation and comprehensive AI design management capabilities. Create API endpoints for customizer operations, AI processing, and theme management with customizer optimization algorithms and AI enhancement systems. Include Liquid code generation, responsive design, and performance optimization for comprehensive AI Shopify theme customizer system and design optimization. Add A/B testing, mobile optimization, and accessibility compliance for enhanced design success and AI platform growth.