feat: Implement custom EventEmitter, RateLimiter, and TTLCache classes

feat: Implement comprehensive email service with multiple providers

feat: Implement authentication service with JWT, password management, and user registration/login functionality

feat: Implement user authentication and management routes with validation and error handling

feat: Add middleware for JWT authentication, error handling, and request logging

feat: Add comprehensive JWT authentication system with security features, including environment configuration, API documentation, and middleware integration

Add services for order, product, and user management with pagination and validation utilities

feat: Implement user, product, and order models with validation middleware

feat: Implement Express middleware patterns and error handling

Add Express.js introduction module with routing examples, API routes, and interactive demo

Add Node.js File System, Streams & Buffers module with examples and utility class

Add comprehensive Node.js Event Loop and Asynchronous Programming module with examples, patterns, and best practices

Add Node.js core modules introduction with examples, best practices, and common mistakes guide

Add initial Node.js introduction module with examples and README