Goodbye lockdown, hello smartphone. As governments race to develop mobile tracing apps to help contain infections, attention is turning to how officials will ensure users’ privacy. The debate is especially urgent in Europe, which has been one of the hardest-hit regions in the world, with nearly 140,000 people killed by COVID-19. The use of monitoring technology, however, may evoke bitter memories of massive surveillance by totalitarian authorities in much of the continent. The European Union has in recent years led the way globally to protect people’s digital privacy, introducing strict laws for tech companies and web sites that collect personal information. Academics and civil liberties activists are now pushing for greater personal data protection in the new apps as well. Here’s a look at the issues.Why an App? European authorities, under pressure to ease lockdown restrictions in place for months in some countries, want to make sure infections …