Meanwhile, her opponent Pam Harbin, a public school watchdog, is supported almost exclusively by grassroots donations.     Both candidates are running for District 4, which serves parts of Squirrel Hill, Point Breeze, Shadyside and North Oakland. Since they’ve cross filed and will appear on both the Republican and Democratic primary ballots, the seat should be decided in the May 21 primary.   Batista and Harbin have raised similar amounts for their campaigns. Harbin has $33,412.95 while Batista has…