fix: Remove undefined ShowEverythingUnavailableToast method call

- Fixes CS0117 compilation error
- Toast notification method was not implemented in AppToastNotificationHelper

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: elliotttate

src/Files.App/Utils/Storage/Search/EverythingSearchEngineService.cs

@@ -100,11 +100,7 @@ private async Task NotifyEverythingUnavailableOnce()
 			{
 				App.Logger?.LogInformation("[SearchEngine: Everything] Showing fallback notification to user");
 
-				// Show toast notification that Everything is unavailable
-				await Task.Run(() =>
-				{
-					AppToastNotificationHelper.ShowEverythingUnavailableToast();
-				});
+				// Everything is not available - search will use Windows Search instead
 			}
 			catch (Exception ex)
 			{