“Whether a federal appellate court may affirm the dismissal of a statutory claim without interpreting the governing statute, without applying the Administrative Procedure Act’s requirement that courts ‘decide all relevant questions of law,’ 5 U.S.C. § 706, and without enforcing mandate-fixed factual predicates established earlier in the same litigation—where the court below treated statutory meaning as irrelevant and relied on factual premises that contradict the litigation’s binding mandate.”
