Louise Blouin, who grew up in a small town in Quebec, rose to the top tiers of society in New York and London a little more than two decades ago. She made a name for herself as an art-world mogul and a host of heady salons and glittering parties filled with artists, scientists, dignitaries and billionaires. But her time as a power player seemed to come to an end on Feb. 13, when she entered a bankruptcy courtroom in Central Islip, N.Y., the