Feature Request: Add Alpha‑5 TLE parsing support

[Chadwuo]

Feature Request: Add Alpha‑5 TLE parsing support

Summary

SGP.NET currently fails to parse modern TLEs using the Alpha‑5 NORAD catalog number format (satellite ID starts with an uppercase letter e.g. A0123). The parser tries to convert the 5‑character field directly to integer and throws a parsing exception.

Alpha‑5 is the official stopgap standard defined by US Space Force / Space‑Track for catalog numbers greater than 99999. Many newly launched satellites and space debris now publish Alpha‑5 TLEs.

Specification reference

Official document: https://www.space-track.org/documentation#/tle-alpha5

Reproduction sample Alpha‑5 TLE

1 A0123U 24001A 26180.41234567 .00000123 00000-0 12345-4 0 9999
2 A0123 45.1234 120.4567 0001234 89.1234 270.5678 14.12345678 12345

Minimal reproduction code

// This line throws parsing exception
var tle = new Tle(line1, line2);

Expected behavior
The parser correctly decode Alpha‑5 5‑character satellite identifier to full NORAD catalog ID.
Normal pure‑numeric TLE (00001–99999) continues working without breaking changes.
Orbital propagation, ground station look angle calculation does not require modification (only metadata parsing).