Build fails at pdf file creation (calibre problem)

```
Creating PDF Output...
67% Running PDF Output plugin
68% Parsed all content for markup transformation
70% Completed markup transformation
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-runner'
WebEngineContext used before QtWebEngine::initialize() or OpenGL context creation failed.
Traceback (most recent call last):
File "/usr/bin/ebook-convert", line 20, in
sys.exit(main())
File "/usr/lib/calibre/calibre/ebooks/conversion/cli.py", line 401, in main
plumber.run()
File "/usr/lib/calibre/calibre/ebooks/conversion/plumber.py", line 1274, in run
self.output_plugin.convert(self.oeb, self.output, self.input_plugin,
File "/usr/lib/calibre/calibre/ebooks/conversion/plugins/pdf_output.py", line 188, in convert
self.convert_text(oeb_book)
File "/usr/lib/calibre/calibre/ebooks/conversion/plugins/pdf_output.py", line 253, in convert_text
convert(
File "/usr/lib/calibre/calibre/ebooks/pdf/html_writer.py", line 1195, in convert
manager = RenderManager(opts, log, container.root)
File "/usr/lib/calibre/calibre/ebooks/pdf/html_writer.py", line 279, in __init__
ans.setUrlRequestInterceptor(self.interceptor)
AttributeError: 'QWebEngineProfile' object has no attribute 'setUrlRequestInterceptor'
```

The report only identifies the PDF creation step and an /usr/bin/ebook-convert traceback; no repository file or test is named. Reproduce the PDF build with the reported calibre environment, then determine whether the QWebEngineProfile API mismatch belongs in the project or its build environment.

Written by the indexing model from the issue text.