A 65-year-old coal miner is admitted for evaluation of chronic lung disease. The patient admits to smoking one pack of cigarettes a day for 40 years. On physical examination, he is noticed to have a barrel chest and use accessory muscles for inspiration. His face is puffy and red. He has 2+ pitting edema of the lower extremities. A chest X-ray is compatible with diffuse fibrosis, with some nodularity in central areas. Which of the following is the most likely diagnosis?