SAN DIEGO — It was a three-person operation based out of a compact, single-story home on Windsong Lane in Escondido — just one small piece of the massive fraud that scammed at least $20 billion in unemployment benefits intended for California workers who lost jobs because of the coronavirus pandemic. But the yearlong scheme conducted by the trio of Ryan Kubista, his wife, Maereichelle Marquez, and Kubista’s mother, Stacy Wright, offers a glimpse into both how easy it was to hijack the funds, and the difficulties investigators face as they continue to pursue swindlers across the state through a…