Fix detach volume client errors to return 409

Author: cursoragent

cmd/api/api/instances.go

@@ -757,7 +757,7 @@ func (s *ApiService) DetachVolume(ctx context.Context, request oapi.DetachVolume
 				Message: err.Error(),
 			}, nil
 		case errors.Is(err, instances.ErrInvalidState), errors.Is(err, volumes.ErrInUse), errors.Is(err, volumes.ErrAmbiguousName):
-			return oapi.DetachVolume500JSONResponse{
+			return oapi.DetachVolume409JSONResponse{
 				Code:    "invalid_state",
 				Message: err.Error(),
 			}, nil