 Drivers for ride-hailing companies in Massachusetts are pushing ahead with what they describe as a first-of-its-kind ballot measure that could win them union rights if approved, despite a landmark settlement last month guaranteeing that Uber and Lyft drivers will earn a minimum pay standard of $32.50 per hour in Massachusetts. Supporters of the measure last week delivered the final batch of signatures needed to land a spot on the November ballot. The Service Employees International Union is making the push and working on a similar effort in California.