PDF conversion hangs indefinitely with do_picture_description=True

Hi Docling team,

I'm encountering an issue where `DocumentConverter` seems to hang indefinitely when converting a PDF with `do_picture_description=True` and `picture_description_options=granite_picture_description`, even when using the CUDA accelerator. The process starts but never completes, even after a long time (one night) and no error is raised.

**Details:**

* CUDA is correctly installed and detected.
* Removing `do_picture_description=True` makes the conversion complete successfully.
* No exception or logging output indicates what the hang might be related to.
* I'm on Windows 10

I'm happy to share the PDF file privately if needed for debugging.

Thanks in advance for your help!