You can create an image that also has the node-red flows. See:
You must copy the
flows_cred.json as well into your image (see link I have shared) otherwise your node-red container won't be able to run the flows.
Currently you are using a volume that is mounted to the folder
/data of your node-red container and as a consequence your node-red flow files (and others) becomes stored in that volume.
Note that once your image is containing the node-red flows then you no longer need to specify this volume.