Flexible Colored Polyurethane PU Foams Market Size & Forecasts 2026-2035, By Segments (Base Material, Density, Processing Technology, Application, Color), Growth Opportunities, Innovation Landscape, Regulatory Shifts, Strategic Regional Insights (U.S., Japan, China, South Korea, UK, Germany, France), and Competitive Dynamics (BASF, Dow, Covestro, Huntsman, Recticel)