Cut over the window to Explorer.Host.exe so only the host writes the index.

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

tests/Explorer.FileOperations.Tests/TransferQueueTests.cs

@@ -316,7 +316,7 @@ public class TransferQueueTests
     {
         await using var ctx = await Harness.CreateAsync();
         var ops = new FileOperationService(ctx.Queue, ctx.Shell, new DiskEnum());
-        var batches = new RenameBatchService(new RenamePlanner(), ctx.Store, ops);
+        var batches = new RenameBatchService(new RenamePlanner(), ctx.Store, new LocalIndexMutations(ctx.Store), ops);
         await ctx.Queue.StartAsync(CancellationToken.None);
         var subjects = new[]
         {