feat: add XLSX export functionality and refactor argument parsing in main script

src/writer.ts

@@ -1,5 +1,8 @@
 import { getDb } from "./database.ts";
 import type { AnalysisResult, SupplierAnalysisResult } from "./types.ts";
+import { mkdirSync } from "node:fs";
+import path from "node:path";
+import * as XLSX from "xlsx";
 
 export type RunCounts = {
   totalProducts: number;
@@ -93,6 +96,22 @@ export function writeResultsToDb(
   console.log(`Results written to SQLite database for run_id: ${runId}`);
 }
 
+export function writeResultsWorkbook(
+  results: AnalysisResult[],
+  outputFile: string,
+): void {
+  const outputDir = path.dirname(outputFile);
+  if (outputDir && outputDir !== ".") {
+    mkdirSync(outputDir, { recursive: true });
+  }
+
+  const workbook = XLSX.utils.book_new();
+  const worksheet = XLSX.utils.json_to_sheet(results.map(buildRow));
+  XLSX.utils.book_append_sheet(workbook, worksheet, "Results");
+  XLSX.writeFile(workbook, outputFile);
+  console.log(`Results workbook written: ${outputFile}`);
+}
+
 export function startRunInDb(
   dbPath: string,
   inputFile: string,