Police officers detain a man in Shanghai, China, amid anti-lockdown protests that have swept the country. Photograph: The New York Times People in the Chinese manufacturing hub of Guangzhou clashed with riot police on Tuesday night, videos on social media showed, as frustration with stringent Covid-19 rules boiled over three years into the pandemic. The clashes in the southern city marked an escalation from protests in the commercial hub of Shanghai, capital Beijing and other cities over the weekend in mainland China's biggest wave of civil disobedience since President Xi Jinping took power a decade ago. In one video posted…