Fix PDF worker serving - add route to serve pdf.worker.min.js from frontend root

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

backend/app.py

@@ -288,6 +288,14 @@ if os.path.exists(frontend_path):
     if os.path.exists(assets_path):
         app.mount("/assets", StaticFiles(directory=assets_path), name="assets")
     
+    # Serve other static files from frontend root (like pdf.worker.min.js)
+    @app.get("/pdf.worker.min.js")
+    async def serve_pdf_worker():
+        pdf_worker_path = os.path.join(frontend_path, "pdf.worker.min.js")
+        if os.path.exists(pdf_worker_path):
+            return FileResponse(pdf_worker_path)
+        raise HTTPException(status_code=404, detail="PDF worker not found")
+    
     @app.get("/")
     async def serve_frontend():
         index_path = os.path.join(frontend_path, "index.html")