Renames the OIDC settings to AUTH_URL, AUTH_SECRET and AUTH_AUTHENTIK_*,
the names Auth.js v5 discovers on its own, which is also what the
api_llm_loxi project already runs against this same Authentik instance.
Matching it means one fewer thing to translate when comparing the two
applications, and no glue code to read the variables manually.
Also settles on a single public domain: the panel and the browser reach
the application on the same origin, so APP_DOMAIN and AUTH_URL cannot
disagree.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012cSY9pVhZmJUKNN7wf1Myd
