feat(pdf-viewer): add postinstall script for pdfjs worker and simplify pdf rendering

scripts/copy-pdfjs-worker.mjs

@@ -0,0 +1,15 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+const src = path.resolve('node_modules/pdfjs-dist/build/pdf.worker.min.mjs');
+const destDir = path.resolve('public/pdfjs-dist');
+const dest = path.join(destDir, 'pdf.worker.min.mjs');
+
+try {
+  fs.mkdirSync(destDir, { recursive: true });
+  fs.copyFileSync(src, dest);
+  console.log(`[pdfjs-dist] Worker copied to: ${dest}`);
+} catch (err) {
+  console.error('[pdfjs-dist] Failed to copy worker:', err);
+  process.exitCode = 1;
+}