On a Wednesday night around 7, Morgan Steffy arrived at El Rey in Philadelphia’s Center City area, following directions from an app she had downloaded two months ago. The app directed the 30-year-old West Philly software engineer to sit at Table 2, where she joined a Temple University doctor, a nomad who works in health care technology, a developer for a finance firm, and this reporter. Steffy didn’t know anyone at the table, but the group of five had come to the restaurant that night for the same reason: to dine with strangers, facilitated by a new app called Timeleft. Over plates of enchilad…