Main menu now lists each registered config.ssh_domains entry as a
choice (selecting one spawns a tab attached to that SSH domain via
SpawnTab), with a single "설정" entry below them that opens what used
to be the main menu (font/connection/other settings, launcher,
reload) -- renamed to show_settings_menu.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>