Baroque flutist and Brookline native Emi Ferguson is known for stretching the boundaries of baroque music, and her new CD features her collaborative bandmates Ruckus, with plenty of surprises. The next time you hear the Handel and Haydn Society, note the earthy and soaring sound of their new principal flutist Emi Ferguson. You can hear that sound on her new CD, too, where she not only spins out Bach’s most profoundly melancholy phrases, but jams with sheer dazzle in arrangements featuring her band Ruckus.