Use current_actor/1 helper in all LiveViews

Replace inconsistent actor access patterns with current_actor/1 helper
and ensure actor is passed to all Ash operations for proper authorization.

lib/mv_web/live/member_live/show.ex

@@ -20,6 +20,7 @@ defmodule MvWeb.MemberLive.Show do
   """
   use MvWeb, :live_view
   import Ash.Query
+  import MvWeb.LiveHelpers, only: [current_actor: 1]
 
   on_mount {MvWeb.LiveHelpers, :ensure_user_role_loaded}
 
@@ -236,7 +237,7 @@ defmodule MvWeb.MemberLive.Show do
 
   @impl true
   def handle_params(%{"id" => id}, _, socket) do
-    actor = socket.assigns[:current_user]
+    actor = current_actor(socket)
 
     # Load custom fields once using assign_new to avoid repeated queries
     socket =