NEW YORK (AP) — Target’s CEO has become the first boss of a major corporation to lose his job over a breach of customer data, showing how responsibility for computer security now reaches right to the top. Gregg Steinhafel, who was also president and chairman, stepped down nearly five months after Target disclosed a huge pre-Christmas breach in which hackers stole millions of customers’ credit- and debit-card records. The theft badly damaged the store chain’s reputation and profits.