Avoid coffee shop laptop squatters by sipping pretty in the adorable herb garden outside Evy Chen’s whimsical Jamaica Plain tea bar, a former auto shop now stockpiled with Chen’s premium cold-brewed tea in flavors like ginger-peach. Her chill brand, the result of an Emerson entrepreneurship program, is blowing up. Chen just rolled out an Airstream trailer-turned-“mobile tea bar,” a second brick-and-mortar opens in Charlestown in July, and a funding round is wrapping up. Tea: spilled.