Add app layout to live_session for dashboard menu

Fix the dashboard missing menu by explicitly setting layout: {FirehoseWeb.Layouts, :app} in the live_session.
This ensures the navigation menu is rendered on the authenticated editor dashboard LiveView.

app/lib/firehose_web/router.ex

@@ -75,6 +75,7 @@ defmodule FirehoseWeb.Router do
     pipe_through [:browser, :require_authenticated_user]
 
     live_session :authenticated_user,
+      layout: {FirehoseWeb.Layouts, :app},
       on_mount: [{FirehoseWeb.UserAuth, :ensure_authenticated}] do
       live "/editor/dashboard", EditorDashboardLive
     end