Ensure self hosted for invite code listing

app/controllers/invite_codes_controller.rb

@@ -1,4 +1,6 @@
 class InviteCodesController < ApplicationController
+  before_action :ensure_self_hosted
+
   def index
     @invite_codes = InviteCode.all
   end
@@ -7,4 +9,10 @@ class InviteCodesController < ApplicationController
     InviteCode.generate!
     redirect_back_or_to invite_codes_path, notice: "Code generated"
   end
+
+  private
+
+    def ensure_self_hosted
+      redirect_to root_path unless self_hosted?
+    end
 end