Three years after the first case of Covid-19 was reported in the central Chinese city of Wuhan, most of the world has learned to live with the disease. Mainland China, however, is only now moving away from its toughest restrictions. The Post’s Thomas Yau has spent much of the past three years living under Covid restrictions in Shanghai, including snap lockdowns that kept him confined to his flat for months at a time. Yau recounts how he and other Shanghai residents coped with the strict zero…