- Add HA_URL and HA_TOKEN environment variables for automatic HA
integration configuration in HA add-on deployments
- Environment variables always override database settings with
non-negotiable precedence; database values preserved for fallback
- Auto-enable integration when both env vars are set; partial config
(one env var) uses database enable state without auto-enabling
- Add centralized get_homeassistant_settings() function following
Spoolman pattern; replace direct database queries across codebase
- Add ha_url_from_env, ha_token_from_env, ha_env_managed fields to
AppSettings schema to inform frontend about configuration source
- UI shows read-only fields with lock icons and "(Environment Managed)"
labels when env-controlled; toggle shows auto-enable badge
- Add comprehensive test coverage: 9 integration + 8 unit tests
Closes#283