Remove Vereinfacht-required logic from settings and member validation

- Member field settings: required only from email + settings (no API override)
- Member resource validation: required fields from settings only
- Gettext: remove obsolete 'Required for Vereinfacht integration' string

lib/mv_web/live/member_live/form.ex

@@ -398,8 +398,6 @@ defmodule MvWeb.MemberLive.Form do
   end
 
   defp get_member_field_required_map do
-    vereinfacht_required? = Mv.Config.vereinfacht_configured?()
-
     case Membership.get_settings() do
       {:ok, settings} ->
         required_config = settings.member_field_required || %{}
@@ -407,20 +405,15 @@ defmodule MvWeb.MemberLive.Form do
 
         Mv.Constants.member_fields()
         |> Enum.map(fn field ->
-          required =
-            field == :email ||
-              (vereinfacht_required? && Mv.Constants.vereinfacht_required_field?(field)) ||
-              Map.get(normalized, field, false)
-
+          required = field == :email || Map.get(normalized, field, false)
           {field, required}
         end)
         |> Map.new()
 
       {:error, _} ->
-        # Email always required; Vereinfacht fields when integration active
+        # When settings cannot be loaded, only email is required
         Map.new(Mv.Constants.member_fields(), fn f ->
-          {f,
-           f == :email || (vereinfacht_required? && Mv.Constants.vereinfacht_required_field?(f))}
+          {f, f == :email}
         end)
     end
   end