Terrified teachers. Obstinate officials. Exhausted parents. Inside the messy, bungled battle to reopen New York City’s schools. — By Keith Gessen In late June, while public-school students across the city were attending their graduation or “step-up” ceremonies over Zoom, the NYC Department of Education, as part of its planning for school reopening in the fall, asked every principal in the system to measure their buildings. Armed with floor…