call_openai() (httpx-based) appends /v1/chat/completions to the upstream
URL. But base_url in the models table typically ends in /v1 (matching the
OpenAI SDK convention used by the resolution job). Combining them produced
/v1/v1/chat/completions → 404 from LM Studio.
Strip a trailing /v1 from the stored base_url before passing it to
call_openai() in the agent routing path.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>