By Brenda Goh and Martin Quin Pollard SHANGHAI/BEIJING (Reuters) – Shanghai announced its first new COVID-19 cases outside quarantined areas in five days on Friday and imposed stricter curbs in two districts, but did not signal any change to the planned end of a prolonged city-wide lockdown on June 1. The commercial hub of 25 million, in its seventh week of lockdown, has been slowly allowing more people to leave their homes in recent days, with many residential compounds issuing passes for brief walks or trips to the supermarket. But in a sign of the challenges of China’s “zero COVID” policy -…