Global Heated Slippers Market Size, Share & Demand Report By Product Type (Battery-Powered, Plug-in Electric, USB-Powered), By Heating Technology (Carbon Fiber, Metal Wire, Graphene-Based), By End-Use (Residential, Medical & Therapeutic, Hospitality & Commercial, Outdoor & Travel), By Distribution Channel (Online, Offline) & By Region – Global Forecasts, 2025–2030