Link carcass and back panel to one finish code

Link materials, finishes and thickness properties in the admin portal so the system applies them automatically, then define the prelam board unit and set its properties.

1. In the admin portal, link materials, finishes and thickness properties so the system applies them automatically.

   ✓ 已于 2026年10月16日 在产品中核实

2. Define the prelam board unit and set properties such as lamination type (internal or external).

   ✓ 已于 2026年10月16日 在产品中核实