refactor: systemd units in services/, read with service_file like patches/

services/steam-desktop-autostart.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Steam Background Autostart for Virtual Keyboard
+After=graphical-session.target
+PartOf=graphical-session.target
+
+[Service]
+Type=simple
+# Only in the Plasma desktop session; gamescope-session starts its own Steam.
+ExecCondition=/bin/sh -c '[ "$XDG_CURRENT_DESKTOP" = KDE ]'
+ExecStart=/usr/bin/steam -silent
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=graphical-session.target