fix: replace SystemEvents with DispatcherTimer to avoid missing package crash

windows/ThemeManager.cs

@@ -2,6 +2,7 @@ using Microsoft.Win32;
 using System;
 using System.Windows;
 using System.Windows.Media;
+using System.Windows.Threading;
 
 namespace ClaudeCheckerWindows;
 
@@ -14,20 +15,17 @@ public static class ThemeManager
     {
         IsDark = ReadIsDark();
         Apply();
-        SystemEvents.UserPreferenceChanged += OnPreferenceChanged;
-    }
 
-    private static void OnPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
-    {
-        if (e.Category != UserPreferenceCategory.General) return;
-        var nowDark = ReadIsDark();
-        if (nowDark == IsDark) return;
-        IsDark = nowDark;
-        Application.Current.Dispatcher.Invoke(() =>
+        var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(5) };
+        timer.Tick += (_, _) =>
         {
+            var nowDark = ReadIsDark();
+            if (nowDark == IsDark) return;
+            IsDark = nowDark;
             Apply();
             ThemeChanged?.Invoke();
-        });
+        };
+        timer.Start();
     }
 
     private static bool ReadIsDark()

windows/UpdateManager.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.Reflection;
 using System.IO;
 using System.IO.Compression;
 using System.Net.Http;
@@ -55,7 +56,11 @@ public class UpdateManager : INotifyPropertyChanged
 
     public string CurrentVersion =>
         System.Reflection.Assembly.GetExecutingAssembly()
-              .GetName().Version?.ToString(3) ?? "1.0.0";
+              .GetCustomAttribute<System.Reflection.AssemblyInformationalVersionAttribute>()
+              ?.InformationalVersion.Split('+')[0]
+              ?? "1.0.0";
+
+    private bool IsPreReleaseBuild => CurrentVersion.Contains('-');
 
     public UpdateManager()
     {
@@ -91,7 +96,8 @@ public class UpdateManager : INotifyPropertyChanged
                 LatestBetaVersion = beta.Version;
                 BetaAvailable     = true;
 
-                if (BetaChannel && IsNewer(beta.Version, LatestVersion))
+                // Show beta update if user opted in, or if they're already running a beta
+                if ((BetaChannel || IsPreReleaseBuild) && IsNewer(beta.Version, LatestVersion))
                 {
                     LatestVersion   = beta.Version;
                     ReleaseNotes    = beta.Notes ?? "";