feat: improve oidc only mode

lib/mv_web/controllers/auth_controller.ex

@@ -15,8 +15,23 @@ defmodule MvWeb.AuthController do
   use AshAuthentication.Phoenix.Controller
 
   alias Mv.Accounts.User.Errors.PasswordVerificationRequired
+  alias Mv.Config
 
-  def success(conn, activity, user, _token) do
+  def success(conn, {:password, :sign_in} = _activity, user, token) do
+    if Config.oidc_only?() do
+      conn
+      |> put_flash(:error, gettext("Only sign-in via Single Sign-On (SSO) is allowed."))
+      |> redirect(to: ~p"/sign-in")
+    else
+      success_continue(conn, {:password, :sign_in}, user, token)
+    end
+  end
+
+  def success(conn, activity, user, token) do
+    success_continue(conn, activity, user, token)
+  end
+
+  defp success_continue(conn, activity, user, _token) do
     return_to = get_session(conn, :return_to) || ~p"/"
 
     message =