fix: give lfx runtime user a home directory

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- LFX runtime user gets a home directory (`useradd -m`, `HOME` set):
+  without one every flow run failed with "Settings service not found".
 ### Security
 - Production ops: `scripts/check_prod.py` validates `.env` secrets and
   modes before deploy (with tests); README production checklist