Both the Hong Kong and Taiwan governments have toughened their stances, each demanding the other side’s cooperation, in an escalating row over the fate of a fugitive murder suspect whose case sparked the city’s extradition bill crisis more than four months ago.Taipei on Monday said Chan Tong-kai’s offer to surrender himself to Taiwan to face charges over the murder of his pregnant girlfriend was not enough, and formal talks were required within a mutual legal assistance framework, while the…