tongxuanzn LLM relay

Routes:
  /v1/*       -> https://www.tongxuanzn.icu/v1/*
  /zai/*      -> https://api.z.ai/api/coding/paas/v4/*
  /grok/v1/*  -> https://grok.19891025.xyz/v1/*

Auth: X-API-Key or ?api_key=
Upstream API key still goes in Authorization.