instant_remote_process() applied its timeout only to Process::timeout(), while the shell-level timeout wrapper around ssh always used the global 3600s default, killing long backups and scheduled tasks at 1h with ssh exit code 255. Also applies the backup timeout to the S3 upload step and makes the default configurable via SSH_COMMAND_TIMEOUT.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
