add landing page

app/controllers/dashboard_controller.rb

@@ -1,7 +1,11 @@
 # frozen_string_literal: true
 
 class DashboardController < ApplicationController
+  skip_before_action :authenticate_user!, only: %i[index]
+
   def index
+    return render 'pages/landing' unless signed_in?
+
     @templates = current_account.templates.active
   end
 end