Add Open in Notepad++ and static Windows shell verbs without embedding IContextMenu on right-click.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/Explorer.Application.Tests/NotepadPlusPlusLocatorTests.cs

@@ -0,0 +1,22 @@
+using Explorer.Application;
+
+namespace Explorer.Application.Tests;
+
+public class NotepadPlusPlusLocatorTests
+{
+    [Fact]
+    public void Finds_notepad_plus_plus_on_PATH()
+    {
+        var found = NotepadPlusPlusLocator.Find(
+            fileExists: p => p.Equals(@"D:\apps\notepad++.exe", StringComparison.OrdinalIgnoreCase),
+            pathVariable: @"C:\Windows;D:\apps");
+        Assert.Equal(@"D:\apps\notepad++.exe", found);
+    }
+
+    [Fact]
+    public void Returns_null_when_missing()
+    {
+        Assert.Null(NotepadPlusPlusLocator.Find(fileExists: _ => false, pathVariable: @"C:\none"));
+        Assert.Contains("Notepad++", NotepadPlusPlusLocator.MissingHint, StringComparison.OrdinalIgnoreCase);
+    }
+}