Check
Aggregated check: current vs latest, sidecar reachability, pulled status.
Safe to call from any same-origin client; respects the origin guard.
Response Body
application/json
curl -X GET "https://example.com/admin/upgrade/check"{ "current_version": "string", "latest_version": "string", "update_available": true, "pulled": false, "is_docker_deploy": true, "auto_update_available": true, "auto_update_reason": "string", "registry_error": "string", "last_checked_at": 0}