A close ally of Mayor Zohran Mamdani — who will help him pick judicial nominees — is a “special” adviser for a Manhattan law firm accused of being involved in a massive insurance fraud scheme, The Post has learned. Ali Najmi — an election attorney whom Hizzoner had referred to as his “brother” and who was a key part of the Democratic socialist’s rise to power — joined the personal injury firm Liakas Law, PC, on the eve of the November election. Experts said Najmi’s role as “special counsel”