PVC Additive Market Size & Forecasts 2026-2035, By Segments (Additive Type, Application, Processing Technology, End-User Industry), Growth Opportunities, Innovation Landscape, Regulatory Shifts, Strategic Regional Insights (U.S., Japan, China, South Korea, UK, Germany, France), and Competitive Dynamics (BASF, Clariant, Arkema, Eastman Chemical, Adeka Corporation)