revert(web): trackball is the default camera control again

feat(web): resizable and minimizable floating windows

fix(web): default to Orbit camera controls, like every other 3D viewer

fix(web): pause decorative CSS animations when the page goes idle

fix(engine): rerun-calibrated camera feel near the orbit pivot

feat(engine): embedding options — size attenuation, control styles, streaming

refactor(web): explicit engine/ boundary, vendored three.js, engine hardening

feat(api,web): delta label protocol — labelling is now O(edit), not O(cloud)