DETROIT—Steady rain drenched the Detroit area Friday, flooding highways and raising the anxiety of frustrated residents whose homes filled with water again exactly three weeks after thousands of basements were wrecked by sewage from a tremendous storm. A downtown ramp to M-10, known as the Lodge Freeway, was below water and closed, while sections of Interstate 94 in Detroit and suburbs were also flooded for hours. The National Weather Service posted a flood warning for Wayne County until late afternoon as well as flood advisories for elsewhere in southeastern Michigan. “When will this end?” Chelsea Parr said on a Facebook page for Grosse Pointe Farms residents. Indeed, people in the Grosse Pointe communities posted remarkable video of water rising in basements from floor drains, geysers in streets and manhole covers rising and falling, apparently from pressure under ground. “Beyond angry,” said Sarah Peruski, standing at the top of the stairs …