Hardcoding /usr/local/share/locked-shutdown-schedule.conf broke once the
hosts/shutdown-schedule file-guard instances moved to guard-lib's own
canonical-path layout. Resolve it at runtime via `guardctl file-guard
canonical-path` instead, and fail loudly if the guard-lib instance isn't
installed rather than silently reading/writing the wrong path.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AFNiYQQgSLAkiBXswyimPq