A 48-year-old woman with severe rheumatoid arthritis and limited mouth opening (2 cm) presents for emergency cesarean section due to fetal distress. Rapid sequence intubation is initiated. After induction with etomidate and succinylcholine, the anesthesiologist attempts direct laryngoscopy but cannot insert the blade due to trismus. Bag-mask ventilation is attempted but is inadequate (SpO₂ 88%, rising EtCO₂ not detected). The patient is now paralyzed and apneic. What is the most appropriate immediate action?