test_eskf.py: 18 tests covering initialization, IMU prediction, VO/satellite
updates, confidence tiers, and full fusion integration.
test_coordinates.py: 17 new tests for K matrix, ray-ground intersection,
pixel-GPS roundtrips, and cv2.perspectiveTransform homography.
All 35 tests pass.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>