WASHINGTON — They’re called managers, and they sometimes work grueling schedules at fast-food chains and retail stores. But with no overtime eligibility, their pay may be lower per hour than many workers they supervise.With those employees in mind, the Obama administration is proposing making up to 5 million more people eligible for overtime — its latest effort to boost pay for lower-income workers. These workers would benefit from rules requiring businesses to pay eligible employees 1½ times their regular pay for any work …