A 42-year-old woman presents with a 3-month history of painful erosions on her buccal mucosa and gingiva. On examination, she has white reticular patches on the oral mucosa with surrounding erythema and ulceration. She also complains of burning sensation while eating. On cutaneous examination, there are violaceous, flat-topped papules on her wrists and shins with a fine white network pattern. Her nails show longitudinal ridging and thinning. What is the most likely diagnosis?