Truck Refrigeration Unit Market Size, Share & Industry Analysis, By System Type (Diesel-engine TRUs, Electric TRUs (eTRUs), and Hybrid TRU), By Sales Channel (Factory-fit and Retrofits), By Vehicle Type (LCV, MCV, and HCV), By Mount Location (Front-mount, Roof-mount, and Under-mount), By End-User Industry (Food & Beverage Logistics, Pharmaceutical & Healthcare, Chemicals, Floriculture & Agricultural Exports, and Retail & E-commerce Grocery), and Regional Forecast, 2026-2034