curl: CVE-2026-3784: wrong proxy connection reuse with credentials

Summary libcurl may reuse an existing HTTP proxy CONNECT tunnel without matching proxy credentials when selecting a reusable connection. In lib/url.c, urlmatchproxyuse calls proxyinfomatches lib/url.c:930-935 → lib/url.c:589-595, and that matcher compares proxy type, host, and port but does not...