Add Models, Services, and Utilities for Bookstore Management

Summary by Bito

The changes in this pull request encompass the addition of various model classes such as Address, Book, Cart, User, and UserRole, which provide a structured way to manage related data. The introduction of service interfaces and their implementations for both Book and User services allows for better separation of concerns and easier management of database operations. Furthermore, utility classes for database connections and common functionalities are included, streamlining the overall architecture. This update significantly enhances the application's functionality and maintainability by establishing clear structures and responsibilities.

Summary by Bito

Implementation of a bookstore management system featuring core model classes (Address, Book, Cart, User), service layer implementations for Book and User management with CRUD operations, and infrastructure components including database utilities and configuration management. The implementation includes session management, user authentication, and shopping cart operations with proper error handling.

Unit tests added: False

Estimated effort to review (1-5, lower is better): 4