The Cubs against the Dodgers. Chicago versus Los Angeles. Carl Sandburg’s “city of the big shoulders” — “stormy, husky, brawling” — taking on the blue-skied, freeway-laced city of the future. A dense tangle of ivy on the outfield walls in one stadium and the clean lines of mid-century architecture in the other. Baseball’s National League Championship Series, which begins Saturday night in Chicago, would seem to be a classic matchup of architectural and even civic opposites.