HTML with show layout bbox is not correctly overlayed

### Bug
I was trying out docling CLI and used the export to HTML with layout overlay. Seems base pdf and overlay do not fit together.

I used only page 2 from https://arxiv.org/pdf/2408.09869v5.pdf
[ExtractPage_code.pdf](https://github.com/user-attachments/files/22864440/ExtractPage_code.pdf)

The output looks like this (Google Chrome):

...

### Steps to reproduce
docling --to html_split_page --show-layout --pipeline vlm --vlm-model granite_docling "ExtractPage_code.pdf"
...

### Docling version
Docling version: 2.55.1
Docling Core version: 2.48.4
Docling IBM Models version: 3.9.1
Docling Parse version: 4.5.0
Python: cpython-311 (3.11.9)
Platform: Windows-10-10.0.22631-SP0
...

### Python version
Python 3.11.9
...

Start by running the reported docling CLI command with ExtractPage_code.pdf and inspect the HTML split-page export and its layout overlay. Trace the --show-layout handling in the HTML export path; done means the generated overlay aligns with the base PDF in the reproduced Chrome view.

Written by the indexing model from the issue text.