♻️ Use pdf-core native lang option

The `setLanguage` workaround manually set the `/Lang` entry in
the PDF catalog using `unsafeOnRender`, `PDFDict`, and `PDFString`.

pdf-core 0.2.0 now supports `lang` as a constructor option on
`PDFDocument`, so the workaround can be replaced with a single
property.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ralfstx

src/render/render-document.ts

@@ -1,5 +1,5 @@
 import type { PDFContext, PDFDict, WriteOptions } from '@ralfstx/pdf-core';
-import { PDFDocument, PDFStream, PDFString } from '@ralfstx/pdf-core';
+import { PDFDocument, PDFStream } from '@ralfstx/pdf-core';
 
 import type { Page } from '../page.ts';
 import type { DocumentDefinition, Metadata } from '../read/read-document.ts';
@@ -10,11 +10,8 @@ export async function renderDocument(
   pages: Page[],
   writeOptions?: WriteOptions,
 ): Promise<Uint8Array> {
-  const pdfDoc = new PDFDocument();
+  const pdfDoc = new PDFDocument({ lang: def.language });
   setMetadata(pdfDoc, def.info);
-  if (def.language) {
-    setLanguage(def.language, pdfDoc);
-  }
   if (def.customData) {
     setCustomData(def.customData, pdfDoc);
   }
@@ -52,13 +49,6 @@ function setMetadata(doc: PDFDocument, info?: Metadata) {
   });
 }
 
-function setLanguage(language: string, doc: PDFDocument) {
-  doc.unsafeOnRender((renderContext) => {
-    const catalog = renderContext.catalog as PDFDict;
-    catalog.set('Lang', PDFString.of(language));
-  });
-}
-
 function setCustomData(data: Record<string, string | Uint8Array>, doc: PDFDocument) {
   for (const [key, value] of Object.entries(data)) {
     doc.unsafeOnRender((renderContext) => {