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

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

src/Explorer.Domain/Abstractions/IIndexStore.cs

@@ -20,6 +20,8 @@ public interface IIndexStore
     ISyncProfileStore SyncProfiles { get; }
     IOperationProfileStore OperationProfiles { get; }
 
+    bool CanWrite { get; }
+
     Task RunWriteAsync(Func<IIndexStore, Task> work, CancellationToken cancellationToken = default);
     Task<T> RunWriteAsync<T>(Func<IIndexStore, Task<T>> work, CancellationToken cancellationToken = default);
 }