Fix empty categories disappearing in unified schema menu builder

The unified schema query used INNER JOIN to children, which excluded
categories with no items. Changed to direct query with NOT EXISTS
template filter so empty categories persist after save+reload.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/menu/getForBuilder.cfm

@@ -205,16 +205,16 @@ try {
         ", { businessID: businessID }, { datasource: "payfrit" });
 
     } else {
-        // NEW UNIFIED SCHEMA: Categories are Items at ParentID=0 with children
+        // NEW UNIFIED SCHEMA: Categories are Items at ParentID=0, CategoryID=0, not templates
         qCategories = queryTimed("
-            SELECT DISTINCT
-                p.ID as CategoryID,
-                p.Name as Name,
+            SELECT
+                p.ID,
+                p.Name,
                 p.SortOrder
             FROM Items p
-            INNER JOIN Items c ON c.ParentItemID = p.ID
             WHERE p.BusinessID = :businessID
               AND p.ParentItemID = 0
+              AND (p.CategoryID = 0 OR p.CategoryID IS NULL)
               AND p.IsActive = 1
               AND NOT EXISTS (
                   SELECT 1 FROM lt_ItemID_TemplateItemID tl WHERE tl.TemplateItemID = p.ID