The Ctrl+A h command menu gains two host-scoped actions: a plain
`herdr update` that streams updater output into the popup, and an
experimental update-and-hot-restart flow that verifies a live server
handoff and reconnects the originating Hub tab once the popup closes.
Remote updates use the remote host's own proxy settings. A standalone
helper reads literal proxy assignments from shell profiles and running
Clash/Mihomo listeners without executing startup files; Windows reads
process, user and machine proxy variables through PowerShell.
