fix: root podman D-Bus cgroup issue in ISO build

When running as sudo, root podman can't reach the systemd D-Bus
session, causing "Transport endpoint is not connected" errors.
Auto-detect and fall back to cgroupfs cgroup manager.

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

image-recipe/build-auto-installer-iso.sh

@@ -186,6 +186,15 @@ check_tools() {
     
     echo "Using container runtime: $CONTAINER_CMD"
 
+    # Fix root podman D-Bus issue (sd-bus: Transport endpoint is not connected)
+    # When running as sudo, systemd cgroup manager can't reach the user D-Bus session.
+    if [ "$CONTAINER_CMD" = "podman" ] && [ "$(id -u)" = "0" ]; then
+        if ! $CONTAINER_CMD run --rm debian:bookworm true 2>/dev/null; then
+            echo "   Root podman D-Bus issue detected, using cgroupfs manager"
+            CONTAINER_CMD="podman --cgroup-manager=cgroupfs"
+        fi
+    fi
+
     # Ensure insecure registry config for Archipelago app registry (HTTP)
     if [ "$CONTAINER_CMD" = "podman" ]; then
         mkdir -p /etc/containers/registries.conf.d