GET /api/system/identity (unauthenticated, license-exempt) returns
{app: 'xenia-pos', site_id, venue_name, version, api_version: 1} so a phone
can confirm which venue a server is when pairing and when rediscovering the
server after an IP change. No secrets: SITE_KEY never leaves the server.
/api/system/status now also returns site_id and lan_ip (HOST_IP only - in
Docker any auto-detected address is the unreachable bridge IP).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>