Serving drinks at 30,000 feet and explaining the intricacies of the in-flight entertainment system were all in a day’s work for Singapore Airlines cabin crew until the coronavirus turned the world upside down.Now Geraldine Loo spends her days guiding commuters at the city’s train stations, while colleague Norazillah Zayadi is working shifts in a hospital.These are just some of the workers who have been redeployed in Singapore as Covid-19 brings some jobs to a standstill and creates surging…