Baby, you’d better be ready for Chipotle, because I put it in friggin’ everything.The U-District boasts a plethora of cheap, family-owned eateries and a liberal, student-dominated clientele that would seem prone to support such ventures. And yet, the undisputed king of the Ave’s fast-food scene is none other than the quick-Mex mega-chain Chipotle, where lines often extend out the door and into the elements.It would surprise us very little, then, if Chipotle’s first downtown Seattle location (1501 4th Ave) up and did the same. The chain’s 10th store in the state opens its doors at 11 a.m. tomorrow, Dec. 4. The burritos, if not the restaurant, will be stuffed. But the restaurant will probably be stuffed as well.