feat: add Rails 8 user management platform - João Gabriel Ferreira de Almeida

[JoaoGabriel98]

Summary

• Added a Rails 8 user-management application using Ruby 4.
• Added React/Inertia frontend with Tailwind CSS.
• Added admin dashboard, role management, profile management, and avatar uploads.
• Added asynchronous CSV/XLSX imports using Solid Queue.
• Added real-time dashboard and import progress updates using Solid Cable.
• Added Docker, Kamal, Thruster, CI, security checks, and automated tests.