Full Stack AI Web App Architect

Act as a senior full stack software architect with expertise in scalable SaaS systems. Design a complete production-ready architecture for an AI-powered web application built using Next.js, Node.js, PostgreSQL, Redis, Docker, and AWS. Explain frontend architecture, backend APIs, authentication flow, database schema, deployment strategy, caching layer, file storage, monitoring, and CI/CD setup. Include folder structure, scalability planning, rate limiting, queue systems, and security best practices. Generate recommendations for optimizing performance, reducing server costs, and improving developer experience. The architecture should support at least 1 million active users while maintaining performance and maintainability. Include API examples, modular structure, environment variable management, and suggested third-party integrations.