Auth route /whoami for nginx subrequest auth, support changing the session cookie domain for that purpose

config/dev.exs

@@ -26,6 +26,8 @@ config :sso_bsn, SsoBsnWeb.Endpoint,
     tailwind: {Tailwind, :install_and_run, [:default, ~w(--watch)]}
   ]
 
+config :sso_bsn, :session_domain, "localhost"
+
 # ## SSL Support
 #
 # In order to use HTTPS in development, a self-signed