Rising rent and shrinking floor plans have made in-unit laundry a luxury. For renters, students and small households stuck feeding quarters into basement machines or hauling baskets to the laundromat, a portable washing machine has become a workaround worth understanding before your next lease. These compact appliances shrink the wash-and-spin process into a unit that can roll up to a kitchen sink, sit on a countertop or fold into a closet. They are not a full replacement for a traditional washer. But for people short on space and hookups, they can turn laundry day into a much smaller chore....