Modernize collaborative pixel art platform to production-ready architecture

Major refactor from simple HTML/JS app to modern full-stack TypeScript application:

## Architecture Changes
- Migrated to monorepo structure with workspaces (backend, frontend, shared)
- Backend: Node.js + Express + TypeScript + Socket.IO
- Frontend: Next.js 15.5 + React 19 + TypeScript + Tailwind CSS
- Shared: Common types and utilities across packages

## Key Features Implemented
- Real-time WebSocket collaboration via Socket.IO
- Virtual canvas with chunked loading for performance
- Modern UI with dark mode and responsive design
- Mock database system for easy development (Redis/PostgreSQL compatible)
- Comprehensive error handling and rate limiting
- User presence and cursor tracking
- Infinite canvas support with zoom/pan controls

## Performance Optimizations
- Canvas virtualization - only renders visible viewport
- Chunked pixel data loading (64x64 pixel chunks)
- Optimized WebSocket protocol
- Memory-efficient state management with Zustand

## Development Experience
- Full TypeScript support across all packages
- Hot reload for both frontend and backend
- Docker support for production deployment
- Comprehensive linting and formatting
- Automated development server startup

## Fixed Issues
- Corrected start script paths
- Updated environment configuration
- Fixed ESLint configuration issues
- Ensured all dependencies are properly installed
- Verified build process works correctly

frontend/tailwind.config.js

@@ -0,0 +1,55 @@
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  content: [
+    './src/pages/**/*.{js,ts,jsx,tsx,mdx}',
+    './src/components/**/*.{js,ts,jsx,tsx,mdx}',
+    './src/app/**/*.{js,ts,jsx,tsx,mdx}',
+  ],
+  darkMode: 'class',
+  theme: {
+    extend: {
+      colors: {
+        primary: {
+          50: '#eff6ff',
+          100: '#dbeafe',
+          200: '#bfdbfe',
+          300: '#93c5fd',
+          400: '#60a5fa',
+          500: '#3b82f6',
+          600: '#2563eb',
+          700: '#1d4ed8',
+          800: '#1e40af',
+          900: '#1e3a8a',
+        },
+        gray: {
+          900: '#0f0f0f',
+          800: '#1a1a1a',
+          700: '#2a2a2a',
+          600: '#3a3a3a',
+          500: '#6a6a6a',
+          400: '#9a9a9a',
+          300: '#cacaca',
+          200: '#e0e0e0',
+          100: '#f0f0f0',
+          50: '#fafafa',
+        },
+      },
+      animation: {
+        'fade-in': 'fadeIn 0.5s ease-in-out',
+        'slide-up': 'slideUp 0.3s ease-out',
+        'pulse-slow': 'pulse 3s cubic-bezier(0.4, 0, 0.6, 1) infinite',
+      },
+      keyframes: {
+        fadeIn: {
+          '0%': { opacity: '0' },
+          '100%': { opacity: '1' },
+        },
+        slideUp: {
+          '0%': { transform: 'translateY(10px)', opacity: '0' },
+          '100%': { transform: 'translateY(0)', opacity: '1' },
+        },
+      },
+    },
+  },
+  plugins: [],
+};