Maybe it was a giant house cat. Maybe it was a bobcat. But that tail—that long, thick tail—that tail said mountain lion. It was Wednesday, Jan. 28, at 3:30 p.m. and Victoria Canby had just finished teaching an outdoor art class to fourth and fifth graders at West Marin School. Seated in her car, she checked a few texts before her drive home to San Anselmo. Then she saw the cat on the other side…