docs: add comprehensive project README

[devZenta]

This pull request significantly updates the README.md to provide a comprehensive overview of the project, replacing the previous generic template with detailed documentation. The new README introduces the application, its features, technical stack, setup instructions, API documentation, project structure, database schema, deployment guide, and contribution guidelines. These changes make the README much more useful for new contributors and users.

Project documentation overhaul:

• Added a project introduction, feature list, and technology stack tables to clearly describe the purpose and architecture of the application.
• Provided step-by-step installation and usage instructions, including environment variable setup and database initialization.
• Documented available scripts and API endpoints, including Swagger documentation for REST API.
• Included a detailed project folder structure and database schema diagram for easier navigation and understanding.
• Added deployment instructions, contribution guidelines (with commit conventions), and licensing information to facilitate collaboration and production readiness.