Add no-GUI boot mode and quieter boot diagnostics

iso/overlay/usr/local/bin/bee-gui-gate

@@ -0,0 +1,27 @@
+#!/bin/sh
+# bee-gui-gate — skip starting the local GUI when bee.gui=off is set.
+
+set -eu
+
+cmdline_param() {
+    key="$1"
+    for token in $(cat /proc/cmdline 2>/dev/null); do
+        case "$token" in
+            "$key"=*)
+                echo "${token#*=}"
+                return 0
+                ;;
+        esac
+    done
+    return 1
+}
+
+mode="$(cmdline_param bee.gui || true)"
+case "${mode}" in
+    off|false|0|tty|console|text|nogui)
+        echo "bee-gui-gate: bee.gui=${mode}; skipping lightdm"
+        exit 1
+        ;;
+esac
+
+exit 0