Fix Docker configuration for new backend structure

- Update Dockerfile to use backend.main:app instead of main:app
- Change exposed port from 8000 to 8001
- Fix docker-compose.yml port mapping to 8001:8001
- Update healthcheck to use correct port and /health endpoint
- Remove old main.py from root directory

Docker now correctly runs the new frontend + backend structure.

Dockerfile

@@ -13,7 +13,7 @@ RUN pip install --no-cache-dir -r requirements.txt
 COPY . .
 
 # Expose port
-EXPOSE 8000
+EXPOSE 8001
 
-# Run the application
-CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]
+# Run the application using the new backend structure
+CMD ["uvicorn", "backend.main:app", "--host", "0.0.0.0", "--port", "8001"]