CNCKitchen/scanruler ? reverse-engineered prompt

Build me a web app that runs entirely in the browser for checking 3D scans against the part they’re supposed to match.

I want to be able to load common scan files like STL, OBJ, PLY, 3MF, and STEP, then switch between a few clear workspaces. One should let me click on a scan and fit simple shapes like spheres, cylinders, planes, circles, cones, and torus features, then measure distances and angles between them, including basic tolerance and GD&T style checks. Another should compare the scan to a reference model and color it by deviation, with an automatic align option. I also want a wall thickness view, a 2D measuring mode for flat images or section cuts, and a simple mesh cleanup and reduce tools area.

Make it feel polished and easy to use, with undo and redo, editable results, and a way to save the whole session. Keep everything local by default, and if you need anything current, look up the latest docs online.