(This is part one of a two-part series. Part two will be published on Thursday.)Miami-Dade County had two routes for defeating Brandi McKay’s claims for minimum wage and overtime pay under the Fair Labor Standards Act.The 11th U.S. Circuit Court of Appeals unanimously rejected the first claim — that she was a “volunteer” when she participated in a sixth-month, unpaid program — but it split on the “internship exception,” established by the Supreme Court in Walling v. Portland …