Fix sort order after column reorder on page reload (#1346)

When columns are reordered via colReorder and the page is reloaded,
the saved sort state uses visual column indices. These were sent
directly as initial_order to the server, which interprets them as
original indices — causing the wrong column to be sorted.

Use the saved colReorder mapping to translate visual indices back to
original indices before sending initial_order in the _init request.

assets/controllers/elements/datatables/datatables_controller.js

@@ -113,8 +113,16 @@ export default class extends Controller {
                     return null;
                 }
 
+                //The saved order index is visual (post-reorder). If colReorder state
+                //exists, map it back to the original column index so the server sorts
+                //the correct column. colReorder[visualIndex] == originalIndex.
+                let columnIndex = order[0];
+                if (saved_state.colReorder) {
+                    columnIndex = saved_state.colReorder[columnIndex];
+                }
+
                 return {
-                    column: order[0],
+                    column: columnIndex,
                     dir: order[1]
                 }
             });