Preview-only image: hide all PDF HTML previews; debug flows return only PDF path; pipeline stops building PDF HTML

app.py

@@ -2842,7 +2842,7 @@ def debug_compile_uploaded_zip(zip_file):
             + _pdf_to_iframe_html(pdf_path, height="700px")
         )
         _write_logs(LOG_PATH, logs)
-        return html, str(pdf_path)
+        return "", str(pdf_path)
     except Exception as e:
         logs.append(f"⚠️ preview failed: {e}")
         _write_logs(LOG_PATH, logs)