curl: 28: HTTP/3 UDP path ignores CURL_SOCKOPT_ALREADY_CONNECTED, reconnects callback-provided socket

Summary When CURLOPTSOCKOPTFUNCTION returns CURLSOCKOPTALREADYCONNECTED, the HTTP/3 QUIC UDP code path ignores it and calls connect anyway, silently reassociating the application-provided socket to a different peer. The TCP path has the correct check. This violates the documented callback contrac...