sagemathgh-39325: [DOC] Allow Sphinx PDF build to reflow long decimal expansions in code-blocks to avoid them extending beyond page limits
    
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Update conf.py's for A Tour of Sage in PDF format to fix long decimal
expansions.

Before:

![Capture d’écran 2025-01-14 à 12 28 46](https://github.com/user-
attachments/assets/34619477-6940-4b75-9655-b4a29f74cbce)

![Capture d’écran 2025-01-14 à 12 27 29](https://github.com/user-
attachments/assets/bcdd363e-b78e-4e1f-beaa-c069fcc10c17)

After:

![Capture d’écran 2025-01-14 à 12 09 05](https://github.com/user-
attachments/assets/000d6148-43d6-4a14-8fcd-b408f5c5afa0)

Additional notes:  EDIT The below is partially obsolete. The change has
been moved to  `sage_docbuld/conf.py` following
sagemath#39325 (comment)

- I took the "before" screenshot from [official
PDF](https://doc.sagemath.org/pdf/en/a_tour_of_sage/a_tour_of_sage.pdf)
and the "after" from building locally on a checkout of develop branch,
which may explain a number of differences which are not related to the
PR at all,
- the PR only has an impact on wrapping lengthy lines in code-blocks,
- To build the PDFs locally, I copied over the conf.py, index.rst and
image files to a fresh sphinx empty project with some adaptations to
conf.py to avoid importing Sage modules which I did not install in my
environment, because I feared the whole thing might be a very long
process and I am not familiar with Sage and Sage repository. I simply
forked it to be able to submit this PR.
- I removed from the French language conf.py some stuff about `\at`
LaTeX control sequence needing to be undefined to avoid conflict with
babel-french, because I am not aware of Sphinx defining any `\at` at all
in the preamble it creates in output `.tex` file, I suspected this is
long obsolete, there is no `\at` definition to be found in any of Sphinx
LaTeX support files and I have never encountered such an issue in my
practice of Sphinx with French language.
- There is also some special configuration in the Italian conf.py which
I simply copied over, not deleting. Its original syntax extends
`latex_elements['preamble']` but except if there is some import during
the build of some other conf.py, which appears not to be the case, a
direct assignment as done in PR should be equivalent.
- Tests of the PDF builds were done using latest Sphinx (8.1.3 and dev
HEAD).
- As explained above the PDF builds were done manually and not via the
Sage build process which I feared might require me to install a bunch of
additional dependencies, etc... which I did not do.  So please double-
check the effect on a genuine documentation build.

The PR only affects the various A Tour of Sage documents but may perhaps
be profitably extended to more Sage documentation in future.

### 📝 Checklist

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- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

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URL: sagemath#39325
Reported by: Jean-François B.
Reviewer(s): Kwankyu Lee

Author: Release Manager

src/sage_docbuild/conf.py

@@ -647,6 +647,11 @@ def linkcode_resolve(domain, info):
 \makeatother
 """
 
+# Enable "hard wrapping" long code lines (only applies if breaking
+# long codelines at spaces or other suitable places failed, typically
+# this is for long decimal expansions or possibly long string identifiers)
+latex_elements['sphinxsetup'] = "verbatimforcewraps=true"
+
 # Documents to append as an appendix to all manuals.
 # latex_appendices = []