Rewrite with modern stack

backend/.env.example

@@ -0,0 +1,30 @@
+# Server Configuration
+PORT=3001
+NODE_ENV=development
+CORS_ORIGIN=http://localhost:3000
+
+# Security
+JWT_SECRET=your-super-secret-jwt-key-change-in-production
+
+# Database Configuration
+REDIS_URL=redis://localhost:6379
+REDIS_KEY_PREFIX=gaplace:
+
+POSTGRES_HOST=localhost
+POSTGRES_PORT=5432
+POSTGRES_DB=gaplace
+POSTGRES_USER=gaplace
+POSTGRES_PASSWORD=password
+
+# Rate Limiting
+RATE_LIMIT_PIXELS_PER_MINUTE=60
+RATE_LIMIT_PIXELS_PER_HOUR=1000
+RATE_LIMIT_CURSOR_PER_SECOND=10
+
+# Canvas Configuration
+MAX_CANVAS_SIZE=10000
+DEFAULT_CANVAS_SIZE=1000
+CHUNK_SIZE=64
+
+# Logging
+LOG_LEVEL=info