Adds <LlmConfigBootstrap /> in root.tsx that, when localStorage has no
active LLM settings, fetches enabled configurations from arcadia and
seeds the active settings (provider/model/baseURL/secretName + reasoning
effort) from the preferred row. Idempotent and silent on auth failure;
retries on session change.
Selection: prefer metadata.default === true, otherwise first enabled row.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
