Amateur satellite catalog + TLE mirror

Auto-generated every 6 h: the amateur satellite population derived from the SatNOGS DB (CC BY-SA 4.0, (c) SatNOGS / Libre Space Foundation contributors), with orbital elements assembled from the Celestrak amateur and satnogs groups (data courtesy of CelesTrak, Dr. T.S. Kelso) and the SatNOGS TLE API. Nexus installs refresh from this mirror instead of each fetching upstream directly. As an adaptation of BY-SA material these assets are published under CC BY-SA 4.0; the same statement travels inside tles.json's own attribution field, which is the authoritative one (these notes are written once, at creation).