Like many of the small-time truckers who bet big on Convoy, the Seattle freight startup that failed last fall, Angadjot Sandhu didn’t realize the ride was over until it was too late. Sandhu, 37, started using Convoy in 2020 to find jobs for his one-rig trucking business in Kent, Washington. Convoy’s app, a kind of Uber for cargo, let Sandhu bid on freight from local companies more efficiently and often at a better price than through traditional freight brokers. Within a year, Sandhu was so busy hauling Convoy loads that he bought a second truck and hired a second driver. By last October, Sandh…