🛰️ Satellite Shell vs Fibre: Walker-Delta LEO Coverage, Elevation Mask, Doppler and Laser-Link Latency Lab

Design a Walker-delta low-Earth-orbit shell (planes, satellites per plane, altitude, inclination), pick two generic city markers and see satellites above the elevation mask, handovers, Ku-band Doppler and a laser-mesh ping against light in fibre. Checks: Kepler period vs RK4, spherical-cap footprint vs random points; inspired by publicly described large LEO broadband constellations, independent educational model.