Add 3d Assets

Replaces primitive Three.js shapes with actual GLB models in 3D games. Handles both animated characters (using Meshy AI generation with auto-rigging or fallback character libraries) and static world objects (props, buildings, scenery). The implementation is thorough: it uses SkeletonUtils.clone() to avoid T-pose bugs, sets up animation crossfading between idle/walk/run states, configures camera-relative WASD movement, and adds OrbitControls for third-person follow. The Meshy integration is well documented with proper prompt patterns and fallback strategies when API access isn't available. Best fit when you've prototyped gameplay with boxes and spheres and need to make it look like an actual game. The character animation system alone saves hours of boilerplate.