Long lines at a pharmacy in the Vedado neighborhood in Havana, Dec. 14, 2024. Never before have Cubans experienced such a wholesale collapse of the social safety net that the country’s leaders — starting with Fidel Castro — once prided themselves on. (Jorge Luis Baños/The New York Times) By DAVID C. ADAMS and FRANCES ROBLES By all accounts, Cuba is enduring the worst economic moment in the 67-year history of its communist revolution. While the island nation has endured periodic episodes of...