BEIJING — A Korean-American aid worker who lived in China on the border with North Korea for more than a decade has been detained by the Chinese authorities, his lawyer said Thursday. The aid worker, Peter Hahn, who is 73 and escaped from the North many years ago, is suspected of embezzlement and possession of fraudulent receipts, said the lawyer, Zhang Peihong. Mr. Hahn ran a Christian aid agency in Tumen City, a…