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>

config.env

@@ -12,10 +12,24 @@
 # What to monitor
 # ---------------------------------------------------------------------------
 
-# socktop profile names (from ~/.config/socktop/profiles.json), in swipe order.
-# The first is what you land on after one right-to-left swipe from the overview.
-# Any count works; the tiled layout and the carousel adapt automatically.
-SOCKTOP_HOSTS="${SOCKTOP_HOSTS:-rpi-master rpi-worker-1 rpi-worker-2 rpi-worker-3}"
+# What to show, as GROUPS separated by ";". Each group is one screen of the
+# carousel: a tiled overview of its hosts, then each host zoomed full-screen in
+# turn, then on to the next group. Host names are socktop profile names from
+# ~/.config/socktop/profiles.json.
+#
+#   overview(A) -> A1 -> A2 -> ... -> overview(B) -> B1 -> B2 -> ...
+#
+# An optional "@layout" token in a group sets its tmux overview layout
+# (tiled, even-horizontal, even-vertical, main-horizontal, main-vertical).
+# Default is tiled: 4 hosts become quarters, 2 become side-by-side.
+# "@even-vertical" stacks the panes one above the other instead.
+#
+# The example below is the rack display: the four Pis quartered and zoomable,
+# then the Orange Pi and the Debian box stacked and zoomable.
+SOCKTOP_GROUPS="${SOCKTOP_GROUPS:-rpi-master rpi-worker-1 rpi-worker-2 rpi-worker-3 ; orangepi trixie @even-vertical}"
+
+# Legacy single-group form. Used only when SOCKTOP_GROUPS is empty.
+SOCKTOP_HOSTS="${SOCKTOP_HOSTS:-}"
 
 # tmux session name. Change only if it collides with something else.
 SOCKTOP_SESSION="${SOCKTOP_SESSION:-socktop4}"