The NR base image's /data has restrictive ACLs that block chmod on
COPY'd files even as root. Writing start.sh inline with printf + chmod
sidesteps this.
NR's automatic package.json install at container start was slow and
required internet. Move npm install to image build time, preserve the
installed node_modules via an anonymous volume so the bind mount of
./nodered:/data doesn't clobber them.
david