chore: Remove unused SectionDragHandle export

Flagged by knip as unused. Drag handles are rendered inline in
SectionHeader/GroupContainer/TabContainer instead.

Author: alex-fedotyev

packages/app/src/components/DashboardDndComponents.tsx

@@ -172,27 +172,3 @@ export function SortableSectionWrapper({
     </div>
   );
 }
-
-// --- Section drag handle ---
-
-export function SectionDragHandle(props: DragHandleProps) {
-  return (
-    <div
-      {...props}
-      style={{
-        cursor: 'grab',
-        display: 'flex',
-        alignItems: 'center',
-        padding: 2,
-        flexShrink: 0,
-      }}
-      title="Drag to reorder sections"
-      data-testid="section-drag-handle"
-    >
-      <IconGripVertical
-        size={14}
-        style={{ color: 'var(--mantine-color-dimmed)' }}
-      />
-    </div>
-  );
-}