renderer.js: HouseRenderer class that loads house JSON and renders
rooms as 3D geometry - walls with door/window cutouts, floors with
material colors, translucent ceilings, orbit camera controls, room
click selection and highlighting.
index.html: Viewer page with sidebar showing floor switcher and
room list with areas. Click rooms in 3D or sidebar to focus camera.
Uses Three.js via CDN importmap (no build step needed).