Alejandro Paradero Almenarios, 20, makes charcoal in Guantánamo, Cuba, on May 12, 2026. Cuba’s already struggling schools are ending the academic year early because of a crippling fuel shortage caused by the U.S. oil blockade. (Lisette Poole González/The New York Times) By ED AUGUSTIN and FRANCES ROBLES Axisa and Aron Alfonso, 6- and 7-year-old siblings in western Cuba, are luckier than most of their classmates: Their father takes them on their one-mile commute to school on horseback. The…