release 0.8.6

Added

• meshy view <model> shows a local .glb or .gltf in an interactive 3D viewer in the browser. It serves that one model read-only on 127.0.0.1 (for a .gltf, also the buffers and textures in its folder) and uploads nothing. --detach serves from a background process and returns result.url at once, which is what an agent needs to open the model in a panel beside the chat; --no-open prints the URL without opening a browser. The server stops after 30 minutes without a request, or on Ctrl-C. A file without materials, such as an untextured preview, renders as matte grey clay. #54