A 47-year-old man with a history of recent subclinical hepatitis C infection presents complaining of rash and mouth pain for the past week. The rash is pruritic. Examination reveals lesions on his wrists, ankles, and scalp; the lesions are shiny, violaceous, sharply demarcated, confluent papules containing fine white lines in a lacy pattern on their surfaces. Examination of his oropharynx reveals an erosion on the left buccal mucosa with the same fine white reticulation. Which of the following is the most likely diagnosis?