Feature: allow PYOK (pass your own key) so we can link to an LLM to assist with NLP for resume review and color scheme generation based upon provided company URL

[athola]

As a user, I would like to be able to pass my own key to assist with resume review and color scheme generation. Please allow any variety of keys if possible such that we can call LLMs using the key: the main ones should be Claude, Codex, GLM/Z.AI, and any others which provide an easy API access for LLM generation