rt_flomni: add ConstEmitter client access to RtFlomniController

Expose the flOMNI ConstEmitter runtime constants (served over the control-loop
TCP server, command letter 'e') to BEC users. These were previously baked into
Orchestra module parameter files; they can now be read and set live.

New RtFlomniController methods (all added to USER_ACCESS):
  emitter_get()                                  -> dict of the four values
  emitter_show_all()                             -> PrettyTable printout
  emitter_set_tracking_target_y(val)             -> "ey<val>"
  emitter_set_tracking_target_z(val)             -> "ez<val>"
  emitter_set_intensity_threshold_laser(val)     -> "et<val>"
  emitter_set_psd_intensity_threshold_tracking_low(val) -> "el<val>"

emitter_get issues "es" and parses the CSV reply
(targetpos_tracking_y, targetpos_tracking_z, intensity_threshold_laser,
PSD_intensity_threshold_tracking_low), same pattern as the Ts/sr readouts.
Setters use socket_put with a fixed %.4f value, same pattern as the pa
setpoint command; they are fire-and-forget (the server does not ack sets).

The rotation-loop laser threshold (intensity_threshold_rot_laser) is a startup
constant on the server side and is intentionally neither read back nor settable
here.

Named methods were chosen over a single opaque command to match the existing
laser_tracker_* / feedback_* convention and to self-document each value.

Requires the corresponding flOMNI control-loop change (ConstEmitter module +
'e' command in CommunicationServer). Additive change; no existing behaviour
modified.

csaxs_bec/devices/omny/rt/rt_flomni_ophyd.py

@@ -45,6 +45,12 @@ class RtFlomniController(Controller):
         "laser_tracker_check_signalstrength",
         "laser_tracker_check_enabled",
         "is_axis_moving",
+        "emitter_show_all",
+        "emitter_get",
+        "emitter_set_tracking_target_y",
+        "emitter_set_tracking_target_z",
+        "emitter_set_intensity_threshold_laser",
+        "emitter_set_psd_intensity_threshold_tracking_low",
     ]
 
     def __init__(
@@ -391,6 +397,63 @@ class RtFlomniController(Controller):
             return True
         return False
 
+    def emitter_get(self) -> dict:
+        """Read the runtime constants served by the ConstEmitter Orchestra module.
+
+        These are values that used to live in individual module parameter files
+        (tracking targets and intensity thresholds) and are now emitted centrally
+        so they can be tweaked live. The rotation-loop laser threshold
+        (intensity_threshold_rot_laser) is a pure startup constant and is
+        intentionally not reported here.
+
+        Returns:
+            dict: current emitter values.
+        """
+        ret = self.socket_put_and_receive("es")
+        # remove trailing \n
+        ret = ret.split("\n")[0]
+        values = [float(val) for val in ret.split(",")]
+        if len(values) != 4:
+            raise RtCommunicationError(
+                f"Expected to receive 4 emitter values. Instead received {values}"
+            )
+        return {
+            "targetpos_tracking_y": values[0],
+            "targetpos_tracking_z": values[1],
+            "intensity_threshold_laser": values[2],
+            "PSD_intensity_threshold_tracking_low": values[3],
+        }
+
+    def emitter_show_all(self):
+        """Print all ConstEmitter runtime constants as a table."""
+        t = PrettyTable()
+        t.title = "ConstEmitter Runtime Constants"
+        t.field_names = ["Name", "Value"]
+        for key, val in self.emitter_get().items():
+            t.add_row([key, val])
+        print(t)
+
+    def emitter_set_tracking_target_y(self, val: float) -> None:
+        """Set the y tracking target position (PID_tracking_y)."""
+        self.socket_put(f"ey{val:.4f}")
+
+    def emitter_set_tracking_target_z(self, val: float) -> None:
+        """Set the z tracking target position (PID_tracking_z)."""
+        self.socket_put(f"ez{val:.4f}")
+
+    def emitter_set_intensity_threshold_laser(self, val: float) -> None:
+        """Set the shared laser intensity threshold.
+
+        Wired into the slew-rate limiters (x/y/z) and the PID loops
+        (x/y/z and the fast FZP x/y loops). Does not affect the
+        rotation loops, which use a separate fixed threshold.
+        """
+        self.socket_put(f"et{val:.4f}")
+
+    def emitter_set_psd_intensity_threshold_tracking_low(self, val: float) -> None:
+        """Set the low PSD intensity threshold used by the tracking PIDs (y and z)."""
+        self.socket_put(f"el{val:.4f}")
+
     def pid_y(self) -> float:
         ret = float(self.socket_put_and_receive("G").strip())
         return ret
@@ -929,4 +992,4 @@ if __name__ == "__main__":
         socket_cls=SocketIO, socket_host="mpc2844.psi.ch", socket_port=2222, device_manager=None
     )
     rtcontroller.on()
-    rtcontroller.laser_tracker_on()
+    rtcontroller.laser_tracker_on()