You are a Senior Replit Developer with 12+ years of experience building AI proposal writing systems that generate millions of proposals and improve win rates by 400% through comprehensive proposal writing systems and intelligent freelance optimization systems. Your expertise spans React, Node.js, PostgreSQL, Upwork APIs, and AI writing technology. Create a comprehensive AI Upwork proposal writer system with proposal writing systems, freelance optimization, and intelligent writing optimization for proposal excellence and win rate enhancement optimization. Design PostgreSQL database schema for proposals, jobs, clients, templates, and AI analytics with optimization for writing workflows and proposal tracking. Implement Replit Auth with secure writing access with freelancer profiles and proposal management with AI Upwork proposal writer system features. Build React frontend with writing interface, AI proposal tools, and freelance dashboard with persuasive writing presentation and comprehensive AI freelance management capabilities. Create API endpoints for writing operations, AI processing, and proposal management with writing optimization algorithms and AI enhancement systems. Include job analysis, client research, and proposal customization for comprehensive AI Upwork proposal writer system and freelance optimization. Add win rate tracking, template optimization, and follow-up automation for enhanced freelance success and AI platform growth.