feat: update hbc via hb_install.sh instead of code patching

Server now sends a bare UPD command; client runs hb_install.sh to
reinstall from the package registry, then restarts. hb_install.sh
also copies itself alongside hbc on client installs.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

scripts/hb_install.sh

@@ -15,8 +15,14 @@ on_ha=0
 [ -z "$what" ] && what="client"
 
 if [ -d /homeassistant ]; then
-    echo "cannot install in HA, run \"docker exec -it homeassistant $0 $@\""
-    exit 1
+    echo "cannot install in HA, running \"docker exec homeassistant $0 $@\""
+    docker exec homeassistant $0 $@
+    rc=$?
+    if [ $rc -ne 0 ]; then
+        echo "Failed to install heartbeat in HA, please check the logs for more details"
+        exit 1
+    fi
+    exit 0
 fi
 if [ -d /config ]; then
     echo "Installing on HA"
@@ -78,6 +84,9 @@ if [ "$what" = "server" ]; then
 else
     rm -f $where/hbc
     ln -sf $(which hbc) $where/hbc
+    rm -f $where/hb_install.sh
+    cp "$0" $where/hb_install.sh
+    chmod +x $where/hb_install.sh
     if [ $on_ha -eq 1 ]; then
         echo "restarting hbc "
         job=$(grep run_hbc configuration.yaml | sed 's/run_hbc://')