Add initial implementation of CalMiner with project structure, environment setup, and core features

- Create .env.example for environment variables
- Update README with project structure and development setup instructions
- Implement FastAPI application with API routes for scenarios and parameters
- Add database models for scenarios, parameters, and simulation results
- Introduce validation middleware for JSON requests
- Create services for running simulations and generating reports
- Add testing strategy and directory structure in documentation

requirements.txt

@@ -0,0 +1,7 @@
+fastapi
+uvicorn
+sqlalchemy
+psycopg2-binary
+python-dotenv
+pytest
+pytest-cov