PetMagix FastAPI Backend Implementation

This merge request implements the complete FastAPI backend structure for PetMagix.

Changes Include:

Initial project structure setup
FastAPI application configuration
Database models and schemas
Authentication system
API endpoints implementation
Development environment configuration

Technical Details:

FastAPI framework implementation
SQLAlchemy ORM integration
JWT authentication
RESTful API endpoints
Documentation setup

Testing:

All endpoints have been tested locally
Database migrations are included
Authentication flow verified

Next Steps:

Deploy to development environment
Configure CI/CD pipeline
Set up monitoring

Review Notes:

Please check the database schema implementations
Verify API endpoint security measures
Review authentication flow