Fix: dedup task in onCreated callback (duplicate with WS task.created)

src/components/KanbanBoard.tsx

@@ -218,7 +218,7 @@ export default function KanbanBoard({ projectId, projectSlug }: Props) {
           projectSlug={projectSlug}
           initialStatus={createInStatus}
           onClose={() => setCreateInStatus(null)}
-          onCreated={(task) => setTasks((prev) => [...prev, task])}
+          onCreated={(task) => setTasks((prev) => prev.some((t) => t.id === task.id) ? prev : [...prev, task])}
         />
       )}
     </div>