Divided the code into functional modules

Services/Platform/WindowsNotificationService.cs

@@ -0,0 +1,49 @@
+namespace HeartRateMonitorAndroid.Services.Platform
+{
+    /// <summary>
+    /// Windows平台通知服务实现
+    /// </summary>
+    public class WindowsNotificationService : INotificationService
+    {
+        /// <summary>
+        /// 初始化通知服务
+        /// </summary>
+        public void Initialize()
+        {
+            // Windows平台不需要特殊初始化
+        }
+
+        /// <summary>
+        /// 显示心率通知
+        /// </summary>
+        public void ShowHeartRateNotification(int currentHeartRate, double avgHeartRate, int minHeartRate, int maxHeartRate, TimeSpan duration)
+        {
+            string title = "心率监测";
+            string content = $"当前心率: {currentHeartRate} bpm    平均: {avgHeartRate:0} bpm";
+
+#if WINDOWS
+            Platforms.Windows.WindowsNotificationHelper.ShowNotification(title, content);
+#endif
+        }
+
+        /// <summary>
+        /// 取消通知
+        /// </summary>
+        public void CancelNotification()
+        {
+#if WINDOWS
+            Platforms.Windows.WindowsNotificationHelper.CancelNotification();
+#endif
+        }
+
+        /// <summary>
+        /// 显示重连通知
+        /// </summary>
+        public void ShowReconnectionNotification(string title, string message, int attemptCount)
+        {
+#if WINDOWS
+            Platforms.Windows.WindowsNotificationHelper.ShowNotification(title, message);
+#endif
+        }
+    }
+}