pub fn read_secret_stdin() -> SshCliResult<SecretString>Expand description
Reads a password line from stdin (no extra echo).
G-IO-06: rejects payloads larger than MAX_SECRET_STDIN_BYTES with
EX_DATAERR semantics via SshCliError::InvalidArgument.
G-SECDEV-01: returns SecretString immediately (rules: never keep
credentials in bare String after the trust boundary). The read buffer is
zeroize::Zeroizing so leftover CR/LF bytes are scrubbed on drop.