Over the past several months, Chip Wilson, the founder and former C.E.O. of Lululemon, has transformed from a pesky shareholder to a full-throated activist investor waging war against his own athleisure empire. Wilson hasn’t been involved in the business since leaving the board in 2015, but his 8.4 percent stake makes him its largest individual shareholder. Last October, he took out an ad in The Wall Street Journal titled “Lululemon: In a Nosedive,” in which he accused the company of becoming a “lumbering corporate dinosaur” that had “lost its soul.” (For the record: Wilson has historically bristled at being labeled an “activist investor,” but if the four-way stretch fabric fits…)