- Guard against malformed localStorage values (e.g. "provider/") by
validating both parts are non-empty before sending to the server
- Only wire settings fallback when both provider AND modelId are
explicitly provided, preventing mismatched provider/modelId combos
Addresses ISSUE-002 and ISSUE-003 from code quality review.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>