feat(pose_3d): POST /apply + quaternion normalization

tests/test_pose_3d_quaternion.py

@@ -0,0 +1,32 @@
+"""Unit test della normalizzazione quaternion server-side."""
+from __future__ import annotations
+
+import math
+import numpy as np
+import pytest
+
+from presa_mano.api.pose_3d_routes import normalize_quaternion
+
+
+def test_already_normalized_is_unchanged():
+    q = [0.0, 0.0, 0.0, 1.0]
+    out = normalize_quaternion(q)
+    assert np.allclose(out, q)
+
+
+def test_not_normalized_gets_normalized_to_unit_length():
+    # scala 2.0
+    q = [0.0, 0.0, 0.0, 2.0]
+    out = normalize_quaternion(q)
+    norm = math.sqrt(sum(x*x for x in out))
+    assert abs(norm - 1.0) < 1e-9
+
+
+def test_degenerate_zero_quat_raises():
+    with pytest.raises(ValueError, match="degenerate"):
+        normalize_quaternion([0.0, 0.0, 0.0, 0.0])
+
+
+def test_near_zero_quat_raises():
+    with pytest.raises(ValueError, match="degenerate"):
+        normalize_quaternion([1e-9, 0.0, 0.0, 1e-9])