The 0.4x0.4 PlaneGeometry square was a fixed-size proxy that did not
reflect the actual ROI extent — visually misleading. Replace it with
an explicit blue point cloud of the inliers fed to fit_plane_svd, so
the user can see *exactly* which depth pixels the plane was fit on.
- Backend: fit response now returns fit_points_camera (CV frame) instead
of the (parallax-shifted) RGB pixel projection.
- Frontend: drop the purple plane mesh; new three.setFitInliers paints
the inliers in blue. The RGB overlay no longer carries blue dots.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
