curl: CVE-2026-87864: IMAP APPEND plus CRLF conversion command injection

Summary When CURLOPTCRLF is enabled, imapperformappend advertises the original input file size in the IMAP APPEND ... N literal but then transmits the expanded body bare LF → CRLF. The server consumes exactly N bytes as the literal, and the overflow bytes are parsed as new IMAP commands in the sa...