Follow-up for after the JB2 switch

Here are items we left for follow-ups after #274

• build time on CircleCI is significantly longer than it was with JB1. I could easily consider this as a follow-up though.

From rossbar: I'm considering this "resolved" - I'm fairly confident the issue was the tox configuration not passing in the OMP_NUM_THREADS variable to the build environment. I just rebased #279 on main (after the JB2 switch) and re-ran the doc build. The sphinx-based run took 1m43 seconds to build, while JB2 took 1m17s 🚀

• cleaning up build errors and warnings -- currently we don't run with strict (and we didn't run with a similar manner as we were not failing JB1 builds with these broken links either)
• deployment not to a gh-pages branch -- this could probably be done as a follow-up, too and now just use the file we have. (I need to make my other repos consistent, too so can do this repo along with those).
• cleanup environment.yaml, switch to a more modern and reliable solution (eyeing pixi)
• change internal links to be myst syntax so they will have hover overs
  - [ ] Request extended amsmath support for LaTeX math rendering. See e.g. numpy.org/numpy-tutorials/mooreslaw-tutorial#building-moores-law-as-an-exponential-function. cf. jupyter-book/mystmd#2447 this has been worked around, but better LaTeX support would be nicer, which is an upstream issue
• Update README/contributor guide for new JB2 patterns.
• deploy GHA should not run on forks (in fact the CI should not get triggered to run on forks -- add in conditionals)

Examinez #274 et les éléments restants qui ne sont pas cochés, en commençant par la configuration de tox, environment.yaml, le README/contributor guide et le workflow de deployment de GitHub Actions. Confirmez quels avertissements de build, quelle syntaxe des liens, quel comportement du deployment, quels outils d’environnement et quelles conditions de déclenchement depuis des forks s’appliquent encore. C’est terminé lorsque les suites à donner applicables sont terminées ou réparties dans des issues ciblées.