Tests: use code interface for Member create/update (actor propagation)

test/membership/custom_field_value_validation_test.exs

@@ -17,13 +17,14 @@ defmodule Mv.Membership.CustomFieldValueValidationTest do
 
     # Create a test member
     {:ok, member} =
-      Member
-      |> Ash.Changeset.for_create(:create_member, %{
-        first_name: "Test",
-        last_name: "User",
-        email: "test.validation@example.com"
-      })
-      |> Ash.create(actor: system_actor)
+      Mv.Membership.create_member(
+        %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test.validation@example.com"
+        },
+        actor: system_actor
+      )
 
     # Create custom fields for different types
     {:ok, string_field} =