Display validated sources

Source fields are optional and can vary by retrieval provider. Render defensively and keep citation warnings visible.

type Source = {
  title?: string;
  url?: string;
  source?: string;
  official?: boolean;
};

function sourceLabel(source: Source): string {
  return source.title ?? source.source ?? source.url ?? "Source";
}

const sources: Source[] = response.sources ?? response.lessons_used ?? [];
const warnings: string[] = response.citation_warnings ?? [];

Do not infer that all sources are official because official_documentation_used is true. That field only indicates official documentation participated in the analysis. Avoid presenting legacy sources as trusted when the retrieved session includes a citation warning about unknown validation status.