Linden Mayor Derek Armstead, who was caught on tape warning of keeping his community from “being taken over by guys with big hats and curls,” apologized Wednesday for his remarks that became public when a former school official filed a whistleblower lawsuit last week accusing him of antisemitism. At the same time, he accused Paul Oliveira, who served as Linden’s assistant school superintendent — along with Oliveira’s attorney — of attempting to extort $950,000 from Linden taxpayers and students in connection with a proposed settlement offer that the mayor termed a “ransom note.” In a statement…