feat:增加待办提醒功能

lib/models/schedule.dart

@@ -13,6 +13,6 @@ class Schedule {
     required this.endTime,
     this.scheduleTime,
     DateTime? createTime,
-  }) : id = id ?? DateTime.timestamp().microsecond,
-        createTime = DateTime.now();
-}
+  }) : id = id ?? DateTime.now().millisecondsSinceEpoch ~/ 1000,
+       createTime = DateTime.now();
+}