Add queued FFmpeg conversion and finish splitting the window from the host.

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

tests/Explorer.Indexing.Tests/ScannerTests.cs

@@ -1,6 +1,7 @@
 using Explorer.Application;
 using Explorer.Domain;
 using Explorer.Domain.Abstractions;
+using Explorer.FileOperations;
 using Explorer.Indexing;
 using Explorer.Storage.Sqlite;
 using Microsoft.Extensions.Logging.Abstractions;