Add host groups (one tmux window per group) and lightdm --autologin

SOCKTOP_GROUPS splits hosts into ';'-separated groups, each its own tmux
window with an optional @layout. The carousel walks group overview -> each
pane zoomed -> next group overview. SOCKTOP_HOSTS still works as one group.

install.sh --autologin writes a lightdm.conf.d drop-in; uninstall removes it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

uninstall.sh

@@ -12,6 +12,7 @@ BIN="$PREFIX/bin"
 CONF="$PREFIX/etc/socktop-swipe.env"
 XCONF=/etc/X11/xorg.conf.d/99-ignore-touch-socktop-swipe.conf
 BCONF=/etc/X11/xorg.conf.d/10-no-blanking-socktop-swipe.conf
+LCONF=/etc/lightdm/lightdm.conf.d/50-autologin-socktop-swipe.conf
 
 keep_config=no
 [ "${1:-}" = "--keep-config" ] && keep_config=yes
@@ -42,6 +43,11 @@ if [ -e "$BCONF" ]; then
 	echo "removed $BCONF (screen blanking returns after the next X restart)"
 fi
 
+if [ -e "$LCONF" ]; then
+	sudo rm -f "$LCONF"
+	echo "removed $LCONF (login prompt returns at next boot)"
+fi
+
 echo
 echo "Left in place on purpose:"
 echo "  * lisgd            -- remove with: sudo make -C ~/src/lisgd uninstall"