Pancreatic Adenocarcinoma — Double Duct Sign

A 64-year-old smoker presents with 6 weeks of progressive painless jaundice, dark urine, pale stools, and pruritus. He has lost 8 kg and developed new-onset diabetes. On examination, a non-tender gallbladder is palpable. Triple-phase pancreatic protocol CT shows the structure marked **A** — a 3.2-cm hypoattenuating mass in the pancreatic head — with simultaneous dilation of the common bile duct (18 mm) and main pancreatic duct (8 mm), plus upstream pancreatic atrophy. There is no vascular encasement or distant metastasis. EUS-FNA confirms pancreatic ductal adenocarcinoma. Which of the following is the most appropriate next step in management?