Orange, Calif.—Just days before a gunman stormed into an Orange office complex—killing four people and injuring another—an employee at the targeted company posted a cheery message on Facebook. “Happy Sunday to you all,” a Unified Homes real estate broker posted on Facebook, alongside a photo of her desk, accessorized with a pot of pink orchids. “Doing what I love is just the best feeling in the world.” Days later, the scene was significantly grimmer. On March 31 about 5:30 p.m., a man opened fire at the 202 W. Lincoln Avenue building. A nine-year-old boy was among the victims. The Facebook poster was not among the victims, and declined April 1 to comment on the colleagues she lost in the shooting. “This is a very sensitive time for the family,” she said. “We are not going to say anything.” The adult victims were employees of Unified Homes, said a relative, who …