The gateway's system-presence.ts was not detecting the version when
OpenClaw is run as a launchd service, because the daemon-runtime.ts
sets OPENCLAW_SERVICE_VERSION but system-presence.ts only checked
OPENCLAW_VERSION and npm_package_version.
This caused 'openclaw status' to show 'unknown' for the version.
Issue: #18456🤖 AI-assisted (lightly tested)