fix(ui): prevent modal overlays from inheriting margin-top from parent space-y containers

frontend/src/features/triage/ManageColumnsModal.tsx

@@ -125,7 +125,7 @@ export const ManageColumnsModal: React.FC<ManageColumnsModalProps> = ({
   };
 
   return (
-    <div className="fixed inset-0 modal-overlay z-50 flex items-center justify-center p-3 sm:p-4">
+    <div className="fixed inset-0 !m-0 modal-overlay z-50 flex items-center justify-center p-3 sm:p-4">
       <div
         className="w-full max-w-md panel-surface shadow-panel border border-border my-auto flex flex-col max-h-[90vh] overflow-hidden"
         onClick={(e) => e.stopPropagation()}