Sales at US retailers declined a record 16.4% in April after coronavirus lockdowns shuttered much of the economy, cost millions of jobs and caused an unprecedented drop in consumer spending.   Sales also sank by a revised 8.3% in March, making these the worst back-to-back declines in modern American history.   A huge pullback in spending indicates the economy has already entered a deep recession. Economists polled by MarketWatch forecast a nearly 28% decline in second-quarter gross domestic ...