fix docker

Dockerfile

@@ -28,5 +28,7 @@ RUN ls -l /code/output_frames
 ENV PATH="/code/venv/bin:$PATH"
 
 # Use PORT environment variable provided by Railway
-CMD ["uvicorn", "app.main:app", "--host", "${HOST}", "--port", "${PORT}"]
+# CMD ["uvicorn", "app.main:app", "--host", "${HOST}", "--port", "${PORT}"]
 # CMD ["sh", "-c", "uvicorn main:app --host 0.0.0.0 --port ${PORT}"]
+# Use a shell to expand environment variables
+CMD ["sh", "-c", "uvicorn app.main:app --host $HOST --port $PORT"]