v1.0.7

fix(packaging): stop services on package removal (#86)

prerm stopped the group with `systemctl stop ark-os.target`, but the units are WantedBy= (not PartOf=) the target, so stopping the target never propagates to its members -- `apt remove` left every service running with its files deleted out from under it. Stop the units explicitly on remove. Upgrade is left untouched: postinst try-restarts after unpack (keeping the UI/MAVLink up during it) rather than stopping here.