A 54-year-old woman presents with 2-year history of ulcers and scarring on fingertips, 6 months of dysphagia, and 2 days of shortness of breath. BP 170/112 mmHg. Urinary protein ++ (5g/d), urine sediment shows RBCs 10-30/HPF. Enlarged kidneys. CXR shows bilateral lower lobe pulmonary interstitial fibrosis. The most likely diagnosis is: