The nation’s capital will begin a gradual reopening Friday, even as Mayor Muriel Bowser warns that it probably will result in more coronavirus infections. Restaurants will be permitted to seat guests outdoors, barbers and hair salons will open with limited capacity and nonessential businesses will be allowed to offer curbside or front-door pickup services. But nail parlors, gyms and public playgrounds will remain closed and gatherings of more than 10 people will be prohibited. Dog parks, tennis courts and golf courses will reopen, but playground equipment and public pools will remain closed. Sports that involve close contact, including football, soccer and basketball, are still banned. For now, all area business are encouraged to work remotely as much as possible. Bowser said Wednesday that the public health emergency she declared in March will remain in place.