fix: address Copilot review suggestions

- Fix dialog hang when user closes window via X button
  (set TCS result before Close, register Closed event as fallback)
- Replace hardcoded 'cancelled by user' with localized string
- Add ConfigureAwait(false) in scan loop to avoid UI thread
  context switching on every file iteration

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: JusterZhu

src/Services/EncryptionDetectionService.cs

@@ -102,7 +102,7 @@ public async Task<EncryptionScanResult> ScanDirectoryAsync(
         foreach (var filePath in files)
         {
             var relativePath = Path.GetRelativePath(directoryPath, filePath);
-            var suspicious = await Task.Run(() => ScanFile(filePath, relativePath));
+            var suspicious = await Task.Run(() => ScanFile(filePath, relativePath)).ConfigureAwait(false);
 
             if (suspicious != null)
                 result.SuspiciousFiles.Add(suspicious);

src/Services/LocalizationService.cs

@@ -91,6 +91,7 @@ public string this[string key]
             ["Patch.ScanBtnInclude"] = "仍然打包全部文件",
             ["Patch.ScanBtnCancel"] = "取消",
             ["Patch.ScanSkipped"] = "已跳过 {0} 个可疑文件",
+            ["Patch.ScanCancelled"] = "用户取消打包",
             ["Ext.Title"] = "扩展包生成",
             ["Ext.BasicInfo"] = "基本信息",
             ["Ext.Name"] = "名称",
@@ -243,6 +244,7 @@ public string this[string key]
             ["Patch.ScanBtnInclude"] = "Include all files anyway",
             ["Patch.ScanBtnCancel"] = "Cancel",
             ["Patch.ScanSkipped"] = "Skipped {0} suspicious file(s)",
+            ["Patch.ScanCancelled"] = "Packaging cancelled by user",
             ["Ext.Title"] = "Extension Package",
             ["Ext.BasicInfo"] = "Basic Info",
             ["Ext.Name"] = "Name",

src/ViewModels/PatchViewModel.cs

@@ -114,8 +114,8 @@ async Task Build()
                     switch (choice)
                     {
                         case EncryptionDialogChoice.Cancel:
-                            L(_loc.T("Patch.Failed", "cancelled by user"));
-                            Status = _loc.T("Patch.Failed", "cancelled by user");
+                            L(_loc["Patch.ScanCancelled"]);
+                            Status = _loc["Patch.ScanCancelled"];
                             Directory.Delete(tmp, true);
                             return;
                         case EncryptionDialogChoice.SkipSuspicious:
@@ -259,9 +259,13 @@ private static async Task<EncryptionDialogChoice> ShowEncryptionDialogAsync(Encr
             MinWidth = 70
         };
 
-        btnSkip.Click += (_, _) => { dialog.Close(); tcs.TrySetResult(EncryptionDialogChoice.SkipSuspicious); };
-        btnInclude.Click += (_, _) => { dialog.Close(); tcs.TrySetResult(EncryptionDialogChoice.IncludeAll); };
-        btnCancel.Click += (_, _) => { dialog.Close(); tcs.TrySetResult(EncryptionDialogChoice.Cancel); };
+        // Set result *before* Close so the Closed handler doesn't override it
+        btnSkip.Click += (_, _) => { tcs.TrySetResult(EncryptionDialogChoice.SkipSuspicious); dialog.Close(); };
+        btnInclude.Click += (_, _) => { tcs.TrySetResult(EncryptionDialogChoice.IncludeAll); dialog.Close(); };
+        btnCancel.Click += (_, _) => { tcs.TrySetResult(EncryptionDialogChoice.Cancel); dialog.Close(); };
+
+        // If user closes the window via X button or Alt+F4, treat as Cancel
+        dialog.Closed += (_, _) => tcs.TrySetResult(EncryptionDialogChoice.Cancel);
 
         btnPanel.Children.Add(btnSkip);
         btnPanel.Children.Add(btnInclude);
@@ -275,12 +279,7 @@ private static async Task<EncryptionDialogChoice> ShowEncryptionDialogAsync(Encr
         else
             dialog.Show();
 
-        // If user closes the window, treat as cancel
-        await tcs.Task;
-        if (!tcs.Task.IsCompleted)
-            tcs.TrySetResult(EncryptionDialogChoice.Cancel);
-
-        return tcs.Task.Result;
+        return await tcs.Task;
     }
 
     private static void AddRiskGroup(Avalonia.Controls.StackPanel parent, string title,