Fix lint warnings: drop deprecated Name field from snapshot response, check errcheck in benchmark

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/hostagent/server.go

@@ -129,7 +129,6 @@ func (s *Server) CreateSnapshot(
 		return nil, connect.NewError(connect.CodeInternal, fmt.Errorf("create snapshot: %w", err))
 	}
 	return connect.NewResponse(&pb.CreateSnapshotResponse{
-		Name:      msg.Name,
 		SizeBytes: sizeBytes,
 	}), nil
 }