The update_allowed_nodes function was changing ownership of the temp file
before all writes were complete, causing 'Permission denied' errors when
appending the allowed_nodes section.
Root cause:
- mktemp creates file owned by script runner (root)
- chown changed ownership to pulse-sensor-proxy:pulse-sensor-proxy
- Subsequent append (>>) failed because root can't write to the file
Fix: Defer chown until after all writes complete and file is moved to
final location. Ownership is still correctly set on the final config file.
rcourtman
c56155ff6d