Local officials will be lenient at first, but Hong Kong residents should also be cooperative when the city’s Covid-19 contact-tracing app becomes mandatory on Monday for anyone entering government buildings and other facilities, the civil service chief has said. The new requirement, which will make use of the app necessary to gain access to venues ranging from libraries and swimming pools to government offices and wet markets, has raised concerns among groups working with vulnerable groups such as the homeless, who often lack smartphones. But on Sunday, a day in which the city confirmed just one imported Covid-19 infection, an…