feat: wait for enrolled sensors to announce, factory reset them on deletion

lib/localiser/web/channels/sensors_channel.ex

@@ -28,6 +28,16 @@ defmodule Localiser.Web.Channels.SensorsChannel do
     {:noreply, socket}
   end
 
+  def handle_info({:sensor_expected, sensor}, socket) do
+    push(socket, "sensor_expected", render_sensor(sensor))
+    {:noreply, socket}
+  end
+
+  def handle_info({:sensor_enrollment_timeout, sensor_id}, socket) do
+    push(socket, "sensor_enrollment_timeout", %{sensor_id: sensor_id})
+    {:noreply, socket}
+  end
+
   def handle_info(_msg, socket), do: {:noreply, socket}
 
   defp render_sensor(sensor) do