For much of the pandemic, hiring in Seattle and across Washington outpaced the rest of the nation, thanks in part to a red-hot tech sector. But there are growing signs — with lower hiring in tech, education and construction — that Washington’s job market could be, as one economist puts it, “at the top of the roller coaster, about to plummet.” Washington employers added just 1,500 jobs in September, according to the state Employment Security Department’s monthly report posted this week. That’s a huge drop from the nearly 22,000 jobs added in August. And while August was an unusually big month, …