The wife of a city firefighter-turned-soldier who was killed last year in Iraq gave birth to the fallen hero's daughter this week — and named the girl in honor of a father she will never know. "We named her Kristian, after her dad," said an exhausted, but ebullient Sharon Engeldrum, who brought the healthy newborn back to the family's Bronx home in Edgewater Park from Einstein Hospital yesterday. Kristian is the daughter of Christian Engeldrum, a 9/11 hero firefighter and member of Bronx Ladder Co. 61. A National Guard veteran before 9/11, the firefighter re-enlisted after sifting through the rubble...