feat:增加待办排序UI功能

lib/pages/todo_page.dart

@@ -26,6 +26,7 @@ class TodoPageState extends State<TodoPage> {
 
   late List<Todo> _todos;
   TodoTab _currentTab = TodoTab.active;
+  late TodoSortMode _selectedMode = TodoSortMode.time;
 
   // 获取过滤后的待办事项
   List<Todo> get _activeTodos => getActiveTodos(_currentTab, _todos);
@@ -37,7 +38,13 @@ class TodoPageState extends State<TodoPage> {
   @override
   void initState() {
     super.initState();
-    _todos = todoService.getAllTodos();
+    _refreshTodos();
+  }
+
+  void _refreshTodos() {
+    setState(() {
+      _todos = todoService.getAllTodos(_selectedMode);
+    });
   }
 
   @override
@@ -45,6 +52,7 @@ class TodoPageState extends State<TodoPage> {
     return Column(
       children: [
         _buildTodoTabs(),
+        _buildTodoSegment(),
         Expanded(child: _buildActiveTodoList(context)),
       ],
     );
@@ -62,6 +70,36 @@ class TodoPageState extends State<TodoPage> {
     );
   }
 
+  Widget _buildTodoSegment() {
+    final colors = Theme.of(context).colorScheme;
+
+    return SegmentedButton<TodoSortMode>(
+      showSelectedIcon: false,
+      emptySelectionAllowed: false,
+      multiSelectionEnabled: false,
+      segments: [
+        ButtonSegment<TodoSortMode>(
+          value: TodoSortMode.time,
+          icon: Icon(Icons.access_time_filled, size: 16),
+          label: const Text('时间', style: TextStyle(fontSize: 12)),
+        ),
+        ButtonSegment<TodoSortMode>(
+          value: TodoSortMode.priority,
+          icon: Icon(Icons.flag_outlined, size: 16,),
+          label: const Text('优先级', style: TextStyle(fontSize: 12)),
+        ),
+      ],
+      selected: {_selectedMode},
+      onSelectionChanged: (Set<TodoSortMode> newSelection) {
+        setState(() {
+          _selectedMode = newSelection.first;
+        });
+        _refreshTodos();
+      },
+      style: buildSegmentStyle(colors),
+    );
+  }
+
   Widget _buildActiveTodoList(BuildContext context) {
     return _activeTodos.isEmpty
         ? buildEmptyState(context, _currentTab)
@@ -142,9 +180,7 @@ class TodoPageState extends State<TodoPage> {
       );
     }
 
-    setState(() {
-      _todos = todoService.getAllTodos();
-    });
+    _refreshTodos();
 
     if (isSuccess) {
       showSuccessDialog(context, isEditing ? '更新成功' : '添加成功');
@@ -157,9 +193,7 @@ class TodoPageState extends State<TodoPage> {
     await notifyService.cancelNotification(todo.id);
     bool isSuccess = await todoService.deleteTodo(todo);
 
-    setState(() {
-      _todos = todoService.getAllTodos();
-    });
+    _refreshTodos();
 
     if (isSuccess) {
       showSuccessDialog(context, '删除成功');