The /data named volume hides anything Dockerfile COPYs into /data, so
the previous CMD override pointing at /usr/src/bf-settings.js didn't
help — Node-RED's launch script still looks for /data/settings.js by
default, which doesn't exist after the volume overlays.
Solution: entrypoint wrapper copies /usr/src/bf-settings.js to
/data/settings.js on first boot when missing, then exec's npm start.
Subsequent boots keep the user-edited version in the volume.
