Add blocked file type handling to viewer

Updates the InsvBlocker plugin to mark files as blocked and sets a blocked message in the viewer window. The viewer now displays a message for blocked file types instead of attempting to preview them.

QuickLook.Plugin/QuickLook.Plugin.InsvBlocker/Plugin.cs

@@ -45,31 +45,16 @@ public class Plugin : IViewer
 
     public void Prepare(string path, ContextObject context)
     {
-        // Set a minimal window size (1x1 pixels) to make the window as small as possible
-        // This window will be closed immediately in View() before becoming visible
-        context.PreferredSize = new Size { Width = 1, Height = 1 };
+        // Set Ignore to true to display "blocked" in the preview window
+        context.IsBlocked = true;
+        context.Title = $"[BLOCKED] {Path.GetFileName(path)}";
+        context.PreferredSize = new Size(400, 200);
     }
 
     public void View(string path, ContextObject context)
     {
-        // Create an empty text block as content (required to avoid errors)
-        var textBlock = new TextBlock
-        {
-            Text = "",
-            Visibility = Visibility.Collapsed
-        };
-        context.ViewerContent = textBlock;
-        context.IsBusy = false;
-        
-        // Close the window immediately using Send priority for immediate execution
-        // This prevents the window from becoming visible to the user
-        Application.Current?.Dispatcher?.BeginInvoke(new Action(() =>
-        {
-            if (context.Source is Window window)
-            {
-                window.Close();
-            }
-        }), DispatcherPriority.Send);
+        // This should not be called since Ignore is set to true in Prepare
+        // But if called, do nothing
     }
 
     public void Cleanup()

QuickLook/ViewerWindow.Actions.cs

@@ -201,6 +201,19 @@ public partial class ViewerWindow
             return;
         }
 
+        if (ContextObject.IsBlocked)
+        {
+            ContextObject.ViewerContent = new System.Windows.Controls.TextBlock
+            {
+                Text = "This file type is blocked.",
+                HorizontalAlignment = HorizontalAlignment.Center,
+                VerticalAlignment = VerticalAlignment.Center,
+                FontSize = 14,
+            };
+            ContextObject.IsBusy = false;
+            return;
+        }
+
         SetOpenWithButtonAndPath();
 
         // Revert UI changes