human? helper method on a user

This is cleaner than hard coding `id > 0` in ruby code.

plugins/discourse-narrative-bot/plugin.rb

@@ -154,7 +154,7 @@ after_initialize do
 
   self.add_to_class(:user, :enqueue_narrative_bot_job?) do
     SiteSetting.discourse_narrative_bot_enabled &&
-      self.id > 0 &&
+      self.human? &&
       !self.anonymous? &&
       !self.staged &&
       !SiteSetting.discourse_narrative_bot_ignored_usernames.split('|'.freeze).include?(self.username)