PDF to LaTeX: source, native export and local compilation checks

This is a self-authored, two-page English electronic PDF. Only the PDF
was uploaded to Doc2X. The original authoring TeX was not uploaded.

source-input.pdf is that exact input.
original-product-export.zip is the unmodified native Doc2X ZIP.
project/pdf-latex-demo.tex and project/images/ contain its exact members.
compiled-original.pdf was generated locally with XeLaTeX, TeX Live 2023.
No upload or compilation on Overleaf was performed.

From inside project/, use a TeX installation with the required packages
and fonts, then run twice:
  xelatex -no-shell-escape -interaction=nonstopmode -halt-on-error ./pdf-latex-demo.tex

The exported preamble uses fontspec, STIX Two fonts, Arial, Courier New,
ctex and other packages. Check the compiler and font availability in your
own environment. This example compiles with font-substitution and
marginal-note warnings; it is not a no-warning or identical-layout claim.

Controlled failure tests used separate copies of this original project:
1. pdfLaTeX stops because fontspec requires XeTeX or LuaTeX.
2. XeLaTeX without the images directory stops at the missing JPEG.
3. Restoring the exact images directory permits compilation; the TeX
   source is unchanged, and compiled text matches the complete project.
The excerpts/ folder contains exact diagnostic excerpts from these tests.

Content limits observed in the native output:
- The source chart's top line 'Distance s (m) | Constant-speed model: s = 3t'
  is omitted from the exported JPG crop and the TeX text. Consult the source
  and add a separate explanatory line if that information is needed.
- The three point labels and x-axis label remain visible. The JPG is not
  editable plotting code, and the original vector chart is not recovered.
- Heading style, table borders and page breaks change.
- This sample does not test scanned pages, handwriting, multilingual
  typesetting, citations, bibliography databases or original author macros.

The native ZIP and its members are not repaired or rewritten.
checks.json records hashes, compiler outcomes and observed limitations.
