fix(astrolabe): load pdfjs-dist externally to fix PDF viewer

When viewing PDF chunks in semantic search, the PDF viewer failed with
"can't access private field" errors. This was caused by:

1. CSP blocks web workers (worker-src 'none'), forcing fake worker mode
2. Vite transforms ES private fields in the bundle, but the worker file
   is untransformed, causing incompatible private field implementations
3. Vue's ref() wraps PDFDocumentProxy in a Proxy, which can't access
   ES private fields

Fixed by:
- Loading pdfjs-dist externally via script tag (avoids Vite transform)
- Creating pdfjs-loader.mjs that imports pdf.mjs and sets window.pdfjsLib
- Using Util::addScript() for CSP-compliant script loading with nonces
- Using shallowRef() instead of ref() for pdfDoc to avoid Proxy wrapper
- Setting workerSrc at runtime using OC.linkTo() for correct app path

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

third_party/astrolabe/vite.config.js

@@ -1,7 +1,40 @@
 import { defineConfig } from 'vite'
 import vue from '@vitejs/plugin-vue'
 import { resolve } from 'path'
-import { readFileSync } from 'fs'
+import { readFileSync, copyFileSync, writeFileSync, mkdirSync } from 'fs'
+
+// Plugin to copy PDF.js files to output directory
+// Both pdf.mjs and pdf.worker.mjs are loaded externally to avoid Vite transforming
+// ES private fields, which breaks compatibility with the fake worker fallback
+function copyPdfFiles() {
+  return {
+    name: 'copy-pdf-files',
+    writeBundle() {
+      mkdirSync(resolve(__dirname, 'js'), { recursive: true })
+      // Copy main library
+      copyFileSync(
+        resolve(__dirname, 'node_modules/pdfjs-dist/build/pdf.mjs'),
+        resolve(__dirname, 'js/pdf.mjs')
+      )
+      console.log('Copied pdf.mjs to js/')
+      // Copy worker (loaded by pdfjs at runtime)
+      copyFileSync(
+        resolve(__dirname, 'node_modules/pdfjs-dist/build/pdf.worker.mjs'),
+        resolve(__dirname, 'js/pdf.worker.mjs')
+      )
+      console.log('Copied pdf.worker.mjs to js/')
+      // Create loader script that imports pdf.mjs and sets window.pdfjsLib
+      // This is loaded via script tag before the main app
+      const loaderScript = `// PDF.js loader - imports pdf.mjs and exposes it globally
+// Loaded before main app to make pdfjsLib available as window.pdfjsLib
+import * as pdfjsLib from './pdf.mjs';
+window.pdfjsLib = pdfjsLib;
+`
+      writeFileSync(resolve(__dirname, 'js/pdfjs-loader.mjs'), loaderScript)
+      console.log('Created pdfjs-loader.mjs in js/')
+    }
+  }
+}
 
 // Read app info from info.xml for @nextcloud/vue
 const infoXml = readFileSync(resolve(__dirname, 'appinfo/info.xml'), 'utf-8')
@@ -9,7 +42,7 @@ const appName = infoXml.match(/<id>([^<]+)<\/id>/)?.[1] || 'astrolabe'
 const appVersion = infoXml.match(/<version>([^<]+)<\/version>/)?.[1] || ''
 
 export default defineConfig({
-  plugins: [vue()],
+  plugins: [vue(), copyPdfFiles()],
   define: {
     appName: JSON.stringify(appName),
     appVersion: JSON.stringify(appVersion),