Add --noblank, and fix install.sh exiting early when no relogin is needed

Wall displays must never blank. --noblank applies two layers: an Xorg
ServerFlags snippet with all four timeouts at 0 (covers the DM greeter, and
survives reboots) and an xset line in the i3 autostart (a session or DM can
re-enable the screensaver after X starts). Either alone is insufficient.

Documents the trap that cost time here: `sudo xset ...` targets root's X
connection and silently does nothing, so a `sudo bash noblank.sh` wrapper looks
like it worked while blanking stays fully armed.

Also fixes a latent bug: `[ "$relogin" = yes ] && echo ...` as the final
statement made install.sh exit non-zero under `set -e` -- and skip the closing
instructions -- whenever a relogin was not required.

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

uninstall.sh

@@ -11,6 +11,7 @@ PREFIX=${PREFIX:-/usr/local}
 BIN="$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
 
 keep_config=no
 [ "${1:-}" = "--keep-config" ] && keep_config=yes
@@ -36,6 +37,11 @@ if [ -e "$XCONF" ]; then
 	echo "removed $XCONF (touch returns to X after the next X restart)"
 fi
 
+if [ -e "$BCONF" ]; then
+	sudo rm -f "$BCONF"
+	echo "removed $BCONF (screen blanking returns after the next X restart)"
+fi
+
 echo
 echo "Left in place on purpose:"
 echo "  * lisgd            -- remove with: sudo make -C ~/src/lisgd uninstall"