SEATTLE — The cooling housing market is driving yet another round of layoffs at a Seattle-based company. The online real estate brokerage Redfin plans to lay off 862 employees nationwide and shut down its house-flipping business, RedfinNow, the company announced Wednesday. The layoffs will cut the company’s workforce by at least 13% and include 75 jobs in Washington. The cuts are “awful but we can’t avoid it,” CEO Glenn Kelman told employees in an email sent before 6 a.m. PST. They come in response to the slowing housing market, Kelman wrote, and “this layoff assumes the downturn will last at …