WASHINGTON — The Senate confirmed Janet L. Yellen, a labor economist and former Federal Reserve chair, to be Treasury secretary on Monday, putting in place a key lieutenant to President Biden at a perilous economic moment, as the new administration tries to revive an economy that has been battered by the coronavirus pandemic.By a vote of 84 to 15, the Senate confirmed Ms. Yellen, making her the first woman to hold the top job at Treasury in its 232-year history. Her quick bipartisan confirmation underscored the support she has from both Republicans and Democrats given her previous stint as Fed chair from 2014 …
