feat: 优化异常处理，新增日志记录

Logger.cs

@@ -0,0 +1,36 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace TimerApp
+{
+    public static class Logger
+    {
+        private static readonly string LogFile = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "error.log");
+        private static readonly object LockObj = new object();
+
+        public static void LogError(string message, Exception? ex = null)
+        {
+            try
+            {
+                lock (LockObj)
+                {
+                    var sb = new StringBuilder();
+                    sb.AppendLine($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] ERROR: {message}");
+                    if (ex != null)
+                    {
+                        sb.AppendLine($"Exception: {ex.Message}");
+                        sb.AppendLine($"StackTrace: {ex.StackTrace}");
+                    }
+                    sb.AppendLine(new string('-', 50));
+
+                    File.AppendAllText(LogFile, sb.ToString());
+                }
+            }
+            catch
+            {
+                // Failed to log, nothing we can do
+            }
+        }
+    }
+}