Linux: keep Home running after the last SSH logout and start it at boot #519

Problem

A systemd user service stops when its user's last session ends, and does not start at boot until that user logs in, unless lingering is enabled for the account. On a Jetson or server managed over SSH, Home would still stop at logout and stay down after a reboot. Draft #350 tries to enable lingering and, when that is refused, only prints a warning.

Expected behaviour

• Install says plainly which mode Home is in: "keeps running after you log out and starts at boot" or "runs only while you are logged in".
• Where enabling lingering needs an administrator, the installer asks once and explains why. If the person declines or has no admin rights, it shows the single command to run later and finishes the install.
• Status shows the same mode, so it can be checked later.
• Autostart off and uninstall change only Home's service, never lingering, since other services on the account may rely on it. If the installer enabled lingering, uninstall says so and shows how to turn it off.

Acceptance

On Linux x86-64 and Jetson:

• Install over SSH with the admin step accepted, log out of every session, reconnect: Home still works.
• Reboot without logging in: Home is ready and opens through an SSH tunnel.
• Install without admin rights: install completes, says "only while logged in" and shows the command; status agrees. After running the command, status reports the new mode without reinstalling.
• Autostart off, reboot: Home does not start; lingering unchanged.
• Uninstall: Home's service removed; lingering unchanged; message as above.

Out of scope

macOS (#518). A system-wide service under a dedicated account (#183).

Links

Parent: #518. #350.