fix: Correctly handle sg devices for iSCSI LUNs

dist/adastra-vtl-installer/web-ui/api.php

@@ -325,11 +325,18 @@ function addLun($params) {
         return;
     }
 
+    // Determine backing store type
+    $bstypeParam = '';
+    if (strpos($device, '/dev/sg') === 0) {
+        $bstypeParam = '--bstype sg'; // Use sg (passthrough) for generic scsi devices
+    }
+
     $command = sprintf(
-        'sudo tgtadm --lld iscsi --mode logicalunit --op new --tid %d --lun %d --backing-store %s 2>&1',
+        'sudo /usr/sbin/tgtadm --lld iscsi --mode logicalunit --op new --tid %d --lun %d --backing-store %s %s 2>&1',
         $tid,
         $lun,
-        escapeshellarg($device)
+        escapeshellarg($device),
+        $bstypeParam
     );
 
     $output = [];