The root/sudo decision now reuses `update_cmd_fleet._needs_sudo` (the helper `hermes update`'s
own fleet restart already uses for `sudo -n systemctl --no-ask-password`) instead of a second
euid check. Tests reduced to one parametrized argv invariant (system-scope lifecycle verbs get
`sudo -n`; status and both-units-installed never do) plus the no-passwordless-sudo request
failure. Dashboard docs note the passwordless-sudo requirement on system-scope installs.