By Megan DiTrolio Sourdough starter and TikTok have nothing on Peloton. The fitness brand, with its fervent following, has owned the quarantine market, raking in $1.8 billion last year and growing in paid digital subscriptions by 472 percent since 2020. Dara Treseder, a former exec at Apple and GE, signed on as SVP, head of global marketing and communications, during the…