The nginx catch-all location / used proxy_pass $litellm_backend_url/ which
stripped the URI path, causing /openapi.json to return the Swagger UI HTML
page instead of the actual OpenAPI spec JSON. This broke the Swagger UI
rendering with "Unable to render this definition" error.
Fix: Add a dedicated location /openapi.json block before the catch-all /
that preserves the full path, so LiteLLM returns its valid openapi: 3.1.0
spec JSON at the public endpoint.