grblhal init: boot-time controller-mode dispatch

The init script consults controller_mode in /data/forgefirm.conf:
'cloud' (once that mode exists, with its own service reading the same
key) keeps grblHAL down; grbl, unset, or a missing config starts it.
Board-verified both ways: cloud in the conf leaves the controller
stopped with a clear message, grbl starts and serves normally.

meta-forgefirm/recipes-forgefirm/grblhal-glowforge/grblhal-glowforge/grblhal.init

@@ -11,9 +11,24 @@
 DAEMON=/usr/bin/grblHAL_glowforge
 PIDFILE=/var/run/grblhal.pid
 LOG=/data/glowforge.log
+CONF=/data/forgefirm.conf
+
+# Boot-time controller-mode dispatch: this service runs the machine in
+# GRBL mode. controller_mode = cloud (once that mode exists, with its
+# own service consulting the same key) keeps grblHAL down; anything
+# else - grbl, unset, or no config file - starts it.
+controller_mode() {
+    [ -r $CONF ] || { echo grbl; return; }
+    m=$(sed -n 's/^[ \t]*controller_mode[ \t]*=[ \t]*\([a-z]*\).*/\1/p' $CONF | tail -n 1)
+    echo "${m:-grbl}"
+}
 
 case "$1" in
   start)
+    if [ "$(controller_mode)" = "cloud" ]; then
+      echo "grblHAL not started (controller_mode = cloud)"
+      exit 0
+    fi
     echo "Starting grblHAL"
     start-stop-daemon -S -q -p $PIDFILE -m -b -x /bin/sh -- \
       -c "cd /data && GFSINK=/dev/glowforge exec $DAEMON -p 23 -e /data/EEPROM-glowforge.DAT >> $LOG 2>&1"