Bartender Danny Donaldson knows the velocity of vodka and the g-force of gin. The popular staffer at the Lodge at Sonoma’s Carneros Bistro is a practitioner of ?flairing,? an acrobatic admixture of equal parts bartending and, well, Cirque du Soleil. Bottles soar above Donaldson’s head, twirl behind his back and land ? usually ? in…