feat: Add keyboard navigation to member linking dropdown

lib/mv_web/live/user_live/form.ex

@@ -404,19 +404,7 @@ defmodule MvWeb.UserLive.Form do
 
   def handle_event("member_dropdown_keydown", %{"key" => "Enter"}, socket) do
     return_if_dropdown_closed(socket, fn ->
-      case socket.assigns.focused_member_index do
-        nil ->
-          {:noreply, socket}
-
-        index ->
-          member = Enum.at(socket.assigns.available_members, index)
-
-          if member do
-            handle_event("select_member", %{"id" => member.id}, socket)
-          else
-            {:noreply, socket}
-          end
-      end
+      select_focused_member(socket)
     end)
   end
 
@@ -493,6 +481,18 @@ defmodule MvWeb.UserLive.Form do
     end
   end
 
+  # Select the currently focused member from the dropdown
+  @spec select_focused_member(Phoenix.LiveView.Socket.t()) ::
+          {:noreply, Phoenix.LiveView.Socket.t()}
+  defp select_focused_member(socket) do
+    with index when not is_nil(index) <- socket.assigns.focused_member_index,
+         member when not is_nil(member) <- Enum.at(socket.assigns.available_members, index) do
+      handle_event("select_member", %{"id" => member.id}, socket)
+    else
+      _ -> {:noreply, socket}
+    end
+  end
+
   @spec assign_form(Phoenix.LiveView.Socket.t()) :: Phoenix.LiveView.Socket.t()
   defp assign_form(%{assigns: %{user: user, show_password_fields: show_password_fields}} = socket) do
     form =