fix(kanban): complete refresh button implementation (#584)

- Destructure onRefresh and isRefreshing props in KanbanBoard
- Add refresh button in kanban header with spinning animation
- Button shows 'Refreshing...' text while loading

Fixes incomplete implementation from PR #548

apps/frontend/src/renderer/components/KanbanBoard.tsx

@@ -277,7 +277,7 @@ const DroppableColumn = memo(function DroppableColumn({ status, tasks, onTaskCli
   );
 }, droppableColumnPropsAreEqual);
 
-export function KanbanBoard({ tasks, onTaskClick, onNewTaskClick }: KanbanBoardProps) {
+export function KanbanBoard({ tasks, onTaskClick, onNewTaskClick, onRefresh, isRefreshing }: KanbanBoardProps) {
   const { t } = useTranslation('tasks');
   const [activeTask, setActiveTask] = useState<Task | null>(null);
   const [overColumnId, setOverColumnId] = useState<string | null>(null);
@@ -412,6 +412,21 @@ export function KanbanBoard({ tasks, onTaskClick, onNewTaskClick }: KanbanBoardP
 
   return (
     <div className="flex h-full flex-col">
+      {/* Kanban header with refresh button */}
+      {onRefresh && (
+        <div className="flex items-center justify-end px-6 pt-4 pb-2">
+          <Button
+            variant="ghost"
+            size="sm"
+            onClick={onRefresh}
+            disabled={isRefreshing}
+            className="gap-2 text-muted-foreground hover:text-foreground"
+          >
+            <RefreshCw className={cn("h-4 w-4", isRefreshing && "animate-spin")} />
+            {isRefreshing ? 'Refreshing...' : 'Refresh Tasks'}
+          </Button>
+        </div>
+      )}
       {/* Kanban columns */}
       <DndContext
         sensors={sensors}