A 50-year-old man with stable schizophrenia managed on paliperidone palmitate long-acting injectable presents to establish psychiatric care. He smokes 1.5 packs of cigarettes per day and expresses strong motivation to quit. He has no history of seizures, no current suicidal ideation, and his psychiatric symptoms have been well controlled for over a year. His PMHNP discusses first-line pharmacotherapy options for smoking cessation. What is the most effective single-agent pharmacotherapy?