Replace the bare TCP-connect return in OpcUaClientDriverProbe with a real
OPC UA GetEndpoints discovery handshake (mirroring SelectMatchingEndpointAsync
in the driver). TCP preflight still fast-fails closed ports; the handshake
confirms the remote is actually an OPC UA server, so a live-but-rejecting
non-OPC-UA process now reads RED instead of a false-healthy green.
Joseph Doherty