OAuth PKCE tester

Runs the authorization-code + PKCE happy path against the configured OAuth server and shows the access token it gets back.

client_id
dh_hqrs23RadGGEYymOLhXp5bCxav7hzNxj
scope
crm:contacts:read
redirect_uri
https://boldtrail-partner.verynormalserver.com/callback
authorize_url
https://api-developerhub.boldtrail.com/oauth/authorize
token_url
https://api-developerhub.boldtrail.com/oauth/token