Three locals are in the running for the country's biggest visual art award. Consider it proof-positive that Nova Scotia has one of the richest visual arts scenes in Canada: On Tuesday, the Sobey Award—the country's top prize for visual art—named not one but three local artists to its annual long list. Alan Syliboy, Aislinn Thomas and Séamus Gallagher are among the 25 artists named in the national long list…