fix: add missing USER root before chown step

The chown -R hermes:hermes was running as non-root user 'hermes'
since USER hermes was set earlier. The new upstream base image
(v0.12.0+) has tools/ owned by root, so the chown fails.
Previous base image happened to have tools/ owned by hermes,
making the chown a silent no-op.

ai/hermes/Dockerfile

@@ -78,6 +78,7 @@ ENV CHROME_EXECUTABLE=/opt/hermes/.playwright/chromium/chrome-linux/chrome
 
 # Ensure tools directory and toolsets.py are writable by the hermes runtime user
 # so custom tools can be injected from the persistent volume at startup.
+USER root
 RUN chown -R hermes:hermes /opt/hermes/tools /opt/hermes/toolsets.py
 
 VOLUME [ "/opt/data" ]