FORT LAUDERDALE, Fla. — After a nearly three-month trial, a prosecutor on Tuesday urged jurors to vote to execute Nikolas Cruz, the gunman who murdered 14 students and three staff members in Florida’s deadliest school shooting. The state argued that Cruz’s tumultuous upbringing and years of mental health problems were not enough to outweigh the details of the savage — and methodically planned — rampage at Marjory Stoneman Douglas High in Parkland on Feb. 14, 2018. “The plan was goal directed. It was calculated,” Broward prosecutor Mike Satz told jurors. “It was purposeful, and it was a systema…