fix: make drag-and-drop on category tree persist correctly

Two issues prevented the shelf tree reordering from working:

- The JS used ``onDragStop`` (only fires for drags outside the
  tree) instead of the ``tree.move`` event to send the AJAX
  request. Moved the POST into the ``tree.move`` handler.
- The ``inside`` case used ``appendNode`` (last child), but
  jqTree sends ``inside`` when dropping before the first child.
  Switched to ``prependNode`` so the node lands first.
- Added missing ``before`` case with ``insertBeforeNode``.

app/Repositories/Core/Categories.php

@@ -67,17 +67,15 @@ class Categories
         $category_target = self::getNode($target_id);
 
         switch ($type) {
+            case 'before':
+                return $category->insertBeforeNode($category_target);
             case 'after':
-                $category->afterNode($category_target);
-                break;
+                return $category->insertAfterNode($category_target);
             case 'inside':
-                $category_target->appendNode($category);
-                break;
+                return $category_target->prependNode($category);
             default:
-                $category->afterNode($category_target);
+                return $category->insertAfterNode($category_target);
         }
-
-        return $category->save();
     }
 
     public static function create($data)