Global Solo Travel Market Size, Share, Demand Report By Travel Type (Adventure Travel, Wellness & Spiritual Travel, Cultural & Heritage Travel, Eco & Sustainable Travel, Luxury Travel, Budget Travel), By Traveler Demographics (Millennials, Gen Z, Baby Boomers, Gen X, Women Travelers), By Booking Channel (Online Platforms, Travel Agencies, Direct Bookings, Mobile Apps), By Region & Segment Forecasts, 2025–2030