Update project structure and enhance model persistence

- Added new model and scaler files to .gitignore and output directory.
- Updated Dockerfile to create output/models directory.
- Revised README to include instructions for using a .env file for configuration.
- Enhanced config.py to load database credentials from environment variables.
- Implemented model saving functionality in salary_predictor.py for consistent and inconsistent earners.

Dockerfile

@@ -9,7 +9,7 @@ RUN pip install -r requirements.txt
 
 COPY salary_analytics/ ./salary_analytics/
 
-RUN mkdir -p output/csv output/plots
+RUN mkdir -p output/csv output/plots output/models
 
 ENV PYTHONPATH=/app
 ENV HOST=0.0.0.0
@@ -17,5 +17,4 @@ ENV PORT=8000
 
 EXPOSE 8000
 
-# Use host 0.0.0.0 to allow external connections
 CMD ["uvicorn", "salary_analytics.api:app", "--host", "0.0.0.0", "--port", "8000", "--reload"]