fix(systemd): drop StopWhenUnneeded from sway-session.target

The target reached active then was immediately garbage-collected:
  Reached target sway compositor session
  Stopped target sway compositor session
  Stopping swayr.../Waybar...
Nothing holds a reverse dependency on sway-session.target, so the first
"stop unneeded units" pass (triggered when any Wanted service transitions,
e.g. a ConditionEnvironment skip during the env-import race) found it
unneeded and StopWhenUnneeded=yes tore it down, cascading via PartOf/
BindsTo to every session service. Manual `systemctl --user start` worked
because that starts the service directly, not the GC-prone target.

StopWhenUnneeded has been latent since 030848c; the nix migration's
changed startup timing exposed it. The canonical sway-session.target
omits it; teardown still works via BindsTo=graphical-session.target and
user-manager shutdown at logout (swaymsg exit).

0 files changed, 0 insertions, 0 deletions