Refactor main.py and organize code into separate modules.

[lucianotonet]

Suggested and implemented by the ChatGPT itself 🤯:

• Move FastAPI routes from main.py to modules/routes.py
• Move Pydantic models to modules/models.py
• Move utility function to modules/utils.py
• Simplify main.py to only initialize and run the FastAPI server

[edmar]

Hey Luciano,

I love the reorganization.

Some new features were added in the main branch. Could you please move them to your routes file?