fix: keep root user in Dockerfile (match upstream image)

docker/hermes/Dockerfile

@@ -16,9 +16,6 @@ RUN uv pip install --no-cache-dir \
     numpy \
     faster-whisper
 
-# Switch back to hermes user
-USER hermes
-
 # Health check for voice readiness
 HEALTHCHECK --interval=30s --timeout=10s --start-period=60s --retries=3 \
     CMD python3 -c "import sounddevice, faster_whisper; print('voice deps OK')" || exit 1