fix(task): replace Date.now with nanoid for unique keys and update task interface

src/App.tsx

@@ -22,7 +22,7 @@ function App() {
           value={inputValue}
           onChange={(e) => setInputValue(e.target.value)}
          />
-         <button onClick={() => addTask(inputValue)}>Add</button>
+         <button onClick={() => { addTask(inputValue); setInputValue(''); }}>Add</button>
       </div>
       <div className="task-list">
         {tasks.length === 0 ? (