feat: use llm for fact extraction

src/lib/workflow/fact-extractor.ts

@@ -1,9 +1,25 @@
 import type { ArticleInput, CandidateFactCard } from "../domain/types";
 import { candidateFactCardSchema } from "../domain/validation";
+import { generateValidatedJson } from "../llm/client";
+import {
+  FACT_EXTRACTOR_SYSTEM_PROMPT,
+  buildFactExtractorPrompt,
+} from "../llm/prompts";
 
 export async function extractCandidateFactCard(
   input: ArticleInput,
 ): Promise<CandidateFactCard> {
+  const llmCard = await generateValidatedJson({
+    schema: candidateFactCardSchema,
+    system: FACT_EXTRACTOR_SYSTEM_PROMPT,
+    prompt: buildFactExtractorPrompt(input),
+    temperature: 0.1,
+  });
+
+  return llmCard ?? extractCandidateFactCardFallback(input);
+}
+
+function extractCandidateFactCardFallback(input: ArticleInput): CandidateFactCard {
   const text = `${input.title}\n${input.body}`;
   const uncertainItems: string[] = [];
   const companyFullName = findCompanyFullName(text);