WESTFORD — It was 3 a.m. when 13-year-old Phalla Nol snuck out of her family’s bamboo and thatch shelter at the Mak Mun refugee camp, or “Old Camp,” on the Cambodian border with Thailand. After she and some of the boys from the camp slipped past the guards and into Thailand, they walked along the road in the dark. They knew there were hostile Vietnamese, Khmer Rouge, and thieves all around. They hid when necessary, taking whatever path they could until they reached their destination: a small market filled with stalls. As she moved from vendor to vendor, Nol bought cookies, cupcakes, and candy. Once she was safely back at…