fix(LamNI): push smear composite via new IDSCamera RPC method

dev.cam_xeye.image.put(composite) failed on real hardware --
PreviewSignal is a BECMessageSignal subclass, and BEC hardcodes
rpc_access=False for that signal_info, so the client-side device proxy
never exposes `image` as an attribute at all (confirmed: this is a
structural BEC constraint, not specific to this device -- no existing
RPC surface, device or widget, offers a raw-array setter either).

Add IDSCamera.push_preview_image(data), a small device-server-side
method (alongside the existing get_last_image()) that does
self.image.put(data) from within the device-server process, where
PreviewSignal is a normal ophyd attribute. _push_smear_composite now
calls dev.cam_xeye.push_preview_image(composite) instead of writing to
the signal directly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/tests_bec_ipython_client/test_x_ray_eye_align.py

@@ -395,7 +395,7 @@ def test_push_smear_composite_duty_cycles_live_mode(bec_client_mock):
         False,
         True,
     ]
-    dev_mock.cam_xeye.image.put.assert_called_once_with(composite)
+    dev_mock.cam_xeye.push_preview_image.assert_called_once_with(composite)
 
 
 def test_smear_sweep_max_projection(bec_client_mock):