Remove more obsolete Devise code

The initializer was a no-op override after our Devise upgrade

AGENTS.md

@@ -63,7 +63,6 @@ Warden `Test::Helpers`, DatabaseCleaner (transactional fixtures **off**), ViewCo
   and assert on DB rows / `enqueued_jobs`.
 - **Request/component/mailer/job/model/helper** specs in matching `spec/` subdirs.
   Fixtures live in `spec/fixtures/`; factories in `spec/factories/`.
-- `spec_helper.rb` reloads routes before each `type: :controller` spec (Devise + Rails 8 workaround).
 
 ## Notes & gotchas
 

config/initializers/devise_rails8_patch.rb

@@ -1,11 +0,0 @@
-# See https://alvincrespo.hashnode.dev/rails-8s-lazy-route-loading-devise
-# TODO remove when Devise is fixed
-require 'devise'
-Devise # make sure it's already loaded
-
-module Devise
-  def self.mappings
-    Rails.application.try(:reload_routes_unless_loaded)
-    @@mappings
-  end
-end