feat(LamNI): make camera live-mode poll interval configurable

IDSCamera's live-mode loop had a hardcoded 0.2s sleep (nominal 5 Hz
cap) between frame grabs. Expose it as live_mode_poll_interval_s
(default 0.2, unchanged for existing cameras) and lower it for LamNI's
cam_xeye (0.02s) so exposure/acquisition time, not this artificial
sleep, becomes the real limit on smear-sweep capture rate.

csaxs_bec/device_configs/ptycho_lamni.yaml

@@ -296,6 +296,7 @@ cam_xeye:
     transpose: false
     force_monochrome: true
     m_n_colormode: 1
+    live_mode_poll_interval_s: 0.02
   enabled: true
   onFailure: buffer
   readOnly: false

csaxs_bec/devices/ids_cameras/ids_camera.py

@@ -88,6 +88,7 @@ class IDSCamera(PSIDeviceBase):
         num_rotation_90: int = 0,
         transpose: bool = False,
         force_monochrome: bool = False,
+        live_mode_poll_interval_s: float = 0.2,
         **kwargs,
     ):
         """Initialize the IDS Camera.
@@ -100,10 +101,15 @@ class IDSCamera(PSIDeviceBase):
             m_n_colormode (Literal[0, 1, 2, 3]): Color mode for the camera.
             bits_per_pixel (Literal[8, 24]): Number of bits per pixel for the camera.
             live_mode (bool): Whether to enable live mode for the camera.
+            live_mode_poll_interval_s (float): Delay between frame grabs in
+                the live-mode loop. Lower this for cameras/use cases that
+                need a higher live-mode push rate; the achievable rate is
+                still bounded by the camera's own exposure/acquisition time.
         """
         super().__init__(name=name, prefix=prefix, scan_info=scan_info, **kwargs)
         self._live_mode_thread: threading.Thread | None = None
         self._stop_live_mode_event: threading.Event = threading.Event()
+        self._live_mode_poll_interval_s = live_mode_poll_interval_s
         # Rolling buffer of push timestamps from _live_mode_loop, used to
         # measure the actual live-mode frame rate (see get_live_fps()).
         self._live_frame_times: deque[float] = deque(maxlen=10)
@@ -206,7 +212,7 @@ class IDSCamera(PSIDeviceBase):
                 logger.error(f"Error in live mode loop: {e}")
                 break
             self._live_frame_times.append(time.time())
-            stop_event.wait(0.2)  # 5 Hz
+            stop_event.wait(self._live_mode_poll_interval_s)
         self.cam.set_camera_rate_limiting(False)
 
     def get_live_fps(self) -> float | None: