MAPLE GROVE, Minnesota — Ice crystals clung to the eyelashes, parka hood, beanie hat and headscarf of Ruqayah Nasser as she took a break after her first-ever snow tubing runs in a Minnesota park on a -18 Celsius January morning. She had joined two dozen other members of a group founded by a Somali-American mother in Minneapolis to promote all-seasons activities among Muslim women, who might otherwise feel singled out in the great outdoors, especially when wearing hijabs. “They understand my lifestyle. I don’t have to explain myself,” said Nasser, who recently moved to the Twin Cities from Chicago and