Organize Projects by Folder Based on Type or Tech Stack

[MiguelAntonioRS]

Currently, there is a mix of Spring Boot backend-only, full-stack, and security-focused projects. A clearer folder structure would help users find what they're looking for faster.

Create folders like:
    backend-only/
    fullstack-spring-react/
    security-examples/
    testing-examples/
    data-access-examples/

This improves navigation and makes the repo more maintainable.