In the hills of New Hampshire, a Democratic primary unfolded as both a contest of credentials and a meditation on political inheritance. Stefany Shaheen, daughter of a retiring senator, and Maura Sullivan, a Marine veteran and former federal official, competed Tuesday to claim an open House seat left by a representative ascending toward the Senate. With a margin of roughly two points separating them and votes still being counted, the race reminded observers that in democracy, neither family name nor fundraising advantage guarantees the people's verdict.