U.S. Vice President Kamala Harris on Friday unveiled a set of economic proposals aimed at lowering daily expenses for middle-class and lower-income families, in an attempt to appeal to core groups of voters seen as the key to victory in the November presidential election. Harris, the Democratic nominee for president, laid out her first major policy proposals, focused on food prices, housing, medical costs and taxes, since President Joe Biden abandoned his bid for a second term about a month ago. At a rally in Raleigh in the battleground state of North Carolina, she announced her economic agend…