Switch to the JS-based start page for now

I like the plain homepage more, but for now I just want to get it
running.

app/controllers/about_controller.rb

@@ -1,58 +1,19 @@
 # frozen_string_literal: true
 
 class AboutController < ApplicationController
-  include RegistrationSpamConcern
+  include WebAppControllerConcern
 
-  layout 'public'
+  skip_before_action :require_functional!
 
-  before_action :set_body_classes, only: :show
   before_action :set_instance_presenter
-  before_action :set_expires_in, only: [:more, :terms]
-  before_action :set_registration_form_time, only: :show
-
-  skip_before_action :require_functional!, only: [:more, :terms]
 
   def show
     expires_in(15.seconds, public: true, stale_while_revalidate: 30.seconds, stale_if_error: 1.day) unless user_signed_in?
   end
 
-  def terms; end
-
-  helper_method :display_blocks?
-  helper_method :display_blocks_rationale?
-  helper_method :public_fetch_mode?
-  helper_method :new_user
-
   private
 
-  def markdown
-    @markdown ||= Redcarpet::Markdown.new(Redcarpet::Render::HTML, escape_html: true, no_images: true)
-  end
-
-  def display_blocks?
-    Setting.show_domain_blocks == 'all' || (Setting.show_domain_blocks == 'users' && user_signed_in?)
-  end
-
-  def display_blocks_rationale?
-    Setting.show_domain_blocks_rationale == 'all' || (Setting.show_domain_blocks_rationale == 'users' && user_signed_in?)
-  end
-
-  def new_user
-    User.new.tap do |user|
-      user.build_account
-      user.build_invite_request
-    end
-  end
-
   def set_instance_presenter
     @instance_presenter = InstancePresenter.new
   end
-
-  def set_body_classes
-    @hide_navbar = true
-  end
-
-  def set_expires_in
-    expires_in 0, public: true
-  end
 end