e8ce0602a4
Adds draw_home_marker() in overlay.py (red cross at projected home position) and draw_airspace() in airspace.py (GeoJSON Polygon boundaries in blue, graceful FileNotFoundError handling). Includes airspace fixture and three tests covering all acceptance criteria. All 70 tests pass; ruff check and format clean. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>