Refactor Dockerfile to use entrypoint script, update requirements for bcrypt, and enhance FastAPI app with optional user retrieval and improved error handling

Dockerfile

@@ -11,9 +11,9 @@ COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 COPY app ./app
+COPY docker-entrypoint.sh /docker-entrypoint.sh
+RUN sed -i 's/\r$//' /docker-entrypoint.sh && chmod +x /docker-entrypoint.sh
 
 EXPOSE 8000
 
-USER appuser
-
-CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]
+ENTRYPOINT ["/docker-entrypoint.sh"]