fix(input/gestures): enforce numpy array immutability in HandLandmarks; add CameraCapture tests

- Set points.flags.writeable = False in HandsDetector.detect() so in-place
  mutation of HandLandmarks.points raises ValueError (frozen=True alone does not
  protect numpy array contents)
- Extend test_handlandmarks_is_immutable to assert ValueError on array mutation
- Add test_camera.py with 3 tests covering is_open, frames() yield/break
  behaviour, and context manager release (was at 0% coverage)
- Remove unused `import numpy as np` from camera.py; fix frames() return
  annotation to Iterator (np.ndarray ref removed with the import)

circuitforge_core/input/gestures/camera.py

@@ -10,7 +10,6 @@ from __future__ import annotations
 from typing import Iterator
 
 import cv2
-import numpy as np
 
 
 class CameraCapture:
@@ -39,7 +38,7 @@ class CameraCapture:
     def is_open(self) -> bool:
         return self._cap.isOpened()
 
-    def frames(self) -> Iterator[np.ndarray]:
+    def frames(self) -> Iterator:
         """Yield BGR uint8 frames until camera fails or caller breaks."""
         while self._cap.isOpened():
             ok, frame = self._cap.read()

circuitforge_core/input/gestures/hands.py

@@ -71,6 +71,7 @@ class HandsDetector:
         out: list[HandLandmarks] = []
         for lm, hand in zip(results.multi_hand_landmarks, results.multi_handedness):
             points = np.array([[p.x, p.y, p.z] for p in lm.landmark], dtype=np.float32)
+            points.flags.writeable = False  # enforce immutability of stored array
             out.append(
                 HandLandmarks(
                     points=points,

tests/test_input/test_gestures/test_camera.py

@@ -0,0 +1,48 @@
+import numpy as np
+import pytest
+from unittest.mock import MagicMock, patch
+
+
+@patch("circuitforge_core.input.gestures.camera.cv2")
+def test_is_open_reflects_videocapture_state(mock_cv2):
+    from circuitforge_core.input.gestures.camera import CameraCapture
+
+    mock_cv2.VideoCapture.return_value.isOpened.return_value = True
+    cam = CameraCapture()
+    assert cam.is_open is True
+
+    mock_cv2.VideoCapture.return_value.isOpened.return_value = False
+    cam2 = CameraCapture()
+    assert cam2.is_open is False
+
+
+@patch("circuitforge_core.input.gestures.camera.cv2")
+def test_frames_yields_until_read_fails(mock_cv2):
+    from circuitforge_core.input.gestures.camera import CameraCapture
+
+    frame = np.zeros((480, 640, 3), dtype=np.uint8)
+    mock_cap = MagicMock()
+    mock_cap.isOpened.return_value = True
+    mock_cap.read.side_effect = [
+        (True, frame),
+        (True, frame),
+        (False, None),  # triggers break
+    ]
+    mock_cv2.VideoCapture.return_value = mock_cap
+
+    cam = CameraCapture()
+    collected = list(cam.frames())
+    assert len(collected) == 2
+
+
+@patch("circuitforge_core.input.gestures.camera.cv2")
+def test_context_manager_calls_release(mock_cv2):
+    from circuitforge_core.input.gestures.camera import CameraCapture
+
+    mock_cap = MagicMock()
+    mock_cv2.VideoCapture.return_value = mock_cap
+
+    with CameraCapture() as cam:
+        pass
+
+    mock_cap.release.assert_called_once()

tests/test_input/test_gestures/test_hands.py

@@ -79,7 +79,13 @@ def test_handlandmarks_is_immutable(mock_mp):
     frame = np.zeros((480, 640, 3), dtype=np.uint8)
     result = detector.detect(frame)[0]
     with pytest.raises((AttributeError, TypeError)):
-        result.handedness = "Left"  # frozen dataclass must reject mutation
+        result.handedness = (
+            "Left"  # frozen dataclass must reject attribute reassignment
+        )
+    with pytest.raises(ValueError):
+        result.points[0] = np.array(
+            [1.0, 2.0, 3.0]
+        )  # writeable=False must reject in-place mutation
 
 
 @patch("circuitforge_core.input.gestures.hands.mp")