A 42-year-old man comes to the clinic for progressive fatigue and abdominal distension. Two months ago, he was hospitalized for pleuritic chest pain that improved when he leaned forward and was treated with NSAIDs. Since then, he has developed worsening lower-extremity swelling and early satiety. Vital signs are normal. Exam shows elevated jugular venous pressure with a prominent y descent, hepatomegaly, ascites, and mild bilateral pitting edema. Heart sounds reveal an early diastolic sound shortly after S2. CT of the chest shows pericardial thickening with calcifications. Which of the following is the most likely diagnosis explaining this patient’s current presentation?