feat(perception): add camera ego-motion evidence

tests/test_xgrids_calibrated_projection.py

@@ -13,6 +13,7 @@ from k1link.device_plugins.xgrids_k1.analyze.calibrated_projection import (
     map_points_to_lidar,
     project_map_points_kb4,
     quaternion_xyzw_to_rotation_matrix,
+    unproject_pixels_kb4,
 )
 from k1link.device_plugins.xgrids_k1.calibration_schema import (
     parse_k1_factory_calibration,
@@ -68,6 +69,19 @@ def test_kb4_projection_uses_theta_polynomial_and_rejects_behind_camera() -> Non
     assert projected.source_indices.tolist() == [0, 1]
 
 
+def test_kb4_unprojection_round_trips_camera_directions() -> None:
+    profile = _identity_profile()
+    directions = unproject_pixels_kb4(
+        [[400.0, 300.0], [400.0 + 100.0 * math.pi / 4.0, 300.0]],
+        profile=profile,
+    )
+    np.testing.assert_allclose(
+        directions,
+        [[0.0, 0.0, 1.0], [math.sqrt(0.5), 0.0, math.sqrt(0.5)]],
+        atol=1e-12,
+    )
+
+
 def test_factory_profile_binds_right_main_camera_and_scales_intrinsics() -> None:
     calibration = parse_k1_factory_calibration(
         (FIXTURES / "camera.yaml").read_bytes(),