ssh_deploy() ignored the result of _ssh_deploy and always returned
success, so a failed transfer to one (or all) of the servers in
DEPLOY_SSH_SERVER was silently swallowed. Track the return code across
the loop and return non-zero if any server failed, letting the caller
handle notification.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
