feat: last run frontend (#21369)

The frontend of feat: Persist Variables for Enhanced Debugging Workflow (#20699).

Co-authored-by: jZonG <jzongcode@gmail.com>

web/app/components/workflow/operator/add-block.tsx

@@ -96,7 +96,7 @@ const AddBlock = ({
       onOpenChange={handleOpenChange}
       disabled={nodesReadOnly}
       onSelect={handleSelect}
-      placement='top-start'
+      placement='right-start'
       offset={offset ?? {
         mainAxis: 4,
         crossAxis: -8,