fix: Prevent adding task on Enter key during composition

Author: nannany

ui/src/pages/TaskList/TaskList.tsx

@@ -224,7 +224,7 @@ const TaskList = () => {
 
   // キー入力イベントを処理
   const handleNewTaskKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
-    if (e.key === "Enter") {
+    if (e.key === "Enter" && !e.nativeEvent.isComposing) {
       handleAddTask();
     }
   };