Fix volume path for promptx data due to 'node' user

[sapuser2017]

Fix volume path for promptx data due to 'node' user

[deepracticexc]

Thanks for the contribution! 👍

This fix is correct — docker/Dockerfile declares USER node, so the container runs as the non-root node user (UID 1000), whose home directory is /home/node, not /root. The data volume path should indeed be /home/node/.promptx. PR #574 makes the matching change in docker-compose.yml, so the two should be merged together.

One minor suggestion (non-blocking): docker/README.md still has the line - The container runs as root user near the bottom of the file. That statement is also inconsistent with USER node — it would be good to update it to something like - The container runs as a non-root \node` user`. Feel free to add it to this PR, or it can be fixed in a follow-up after merge.

Thanks again 🙏