v1.2.6 - Satellite groups, navigation & visual improvements

1. Satellite groups - proper categorization: ISS & Stations, Starlink, Navigation, Science & Weather, Other
2. Detail view navigation - Enter now returns to the previous list instead of the main menu
3. Cloud cover - displayed as ☁︎ XX%
4. Azimuth - compass direction added, e.g. 45°NE → 135°SE
5. Moon phase - displayed as Moon XX%
6. Code cleanup

Published - v1.2.5 is now available on GitHub and PyPI