Senator Kamala Harris leaned into her East Bay roots as she held the first official rally of her presidential campaign in Oakland on Sunday. Stepping onto a podium in the shade of a flag-draped Oakland City Hall, Harris waved at the largest crowd ever gathered in her support, unable to contain a broad, excited smile. An estimated 20,000 people poured into Frank H. Ogawa Plaza and overflowed into the streets surrounding Oakland City Hall. Cheers and chants drawing out the…