fix(table): use column label instead of SQL expression for orderby in downloads (#39332)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

superset-frontend/plugins/plugin-chart-ag-grid-table/src/buildQuery.ts

@@ -238,12 +238,11 @@ const buildQuery: BuildQuery<TableChartFormData> = (
         });
 
         if (matchingColumn) {
-          if (
-            typeof matchingColumn === 'object' &&
-            'sqlExpression' in matchingColumn
-          ) {
-            return matchingColumn.sqlExpression;
-          }
+          // Return the label, not the raw sqlExpression. The backend
+          // (helpers.py get_sqla_query) resolves orderby strings by
+          // matching adhoc column labels, then uses adhoc_column_to_sqla
+          // to emit the actual SQL expression into ORDER BY — so this
+          // is dialect-safe across all database engines.
           return getColumnLabel(matchingColumn);
         }