- Add _fetch_iss_realtime() helper function for real-time ISS position
- Satellite position endpoint now uses real-time API for ISS specifically
- Other satellites still use TLE-based calculations
- ISS orbit track still calculated from TLE (for future/past positions)
- Falls back between Open Notify and Where The ISS At APIs
This ensures the satellite dashboard shows accurate ISS position
while maintaining TLE-based tracking for other satellites.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>