Republican Charlie Baker, in his first public comments since Election Day, blamed Treasurer Tim Cahill and fizzling GOP enthusiasm for his defeat in an e-mail to supporters in which he also expressed sadness for failing to deliver a victory. . . . Baker finished 8 points behind Democratic Gov. Deval Patrick — the exact share of the vote the independent Cahill garnered. “A third-party candidate pulling 8 percent made our already narrow window that much narrower,” Baker wrote.