fix:关机时不保存使用数据

Ink Canvas/App.xaml.cs

@@ -338,6 +338,13 @@ namespace Ink_Canvas
                 WriteCrashLog($"最后错误信息: {lastErrorMessage}");
             }
         }
+        
+        // 新增：关机保存使用时间数据
+        private void SystemEvents_SessionEnding(object sender, SessionEndingEventArgs e)
+        {
+             string reason = e.Reason == SessionEndReasons.Logoff ? "用户注销" : "系统关机";
+             DeviceIdentifier.SaveUsageStatsOnShutdown();
+        }
 
         // 新增：记录崩溃日志
         private static void WriteCrashLog(string message)