实现报销材料合并预览与差旅概要（07-27-yang-jun-reimbursement-readiness）

server/src/services/reimbursementMaterialPreviewWorker.js

@@ -0,0 +1,11 @@
+const { parentPort, workerData } = require("node:worker_threads");
+const { mergeMaterialsToPdf } = require("./reimbursementMaterialPdf");
+
+mergeMaterialsToPdf(workerData.materials, workerData.limits)
+  .then(({ buffer, pageCount }) => {
+    const bytes = Uint8Array.from(buffer);
+    parentPort.postMessage({ ok: true, bytes, pageCount }, [bytes.buffer]);
+  })
+  .catch((error) => {
+    parentPort.postMessage({ ok: false, code: error?.message || "material_preview_merge_failed" });
+  });