dsh-3d-model-studio: Preview 3D models and parse Three.js scenes in the DSH right sidebar

`dsh-3d-model-studio` is a DSH client plugin (v0.3.1, MIT) maintained by act27 that previews glb/gltf/fbx and other formats in the right sidebar and exports the runtime Three.js scene—either the entire package or individual objects—to GLB/glTF/FBX/OBJ/STL/PLY. It supports loading HTML or pasting code on the scene export page, writing to split-export for split preview, and the Agent tool `three_export` for conversion and inspection in the workspace. Based on the official README, this article outlines installation commands, typical usage, and security considerations, making it suitable for agents and frontend developers performing model viewing and format conversion within Harness.