KaTeX: drop js script files, use build-time rendering instead

[deining]

This PR fixes #2270.

With > 300 lines dropped (user guide + scripts), this PR significantly simplifies the documentation and the code base for KaTeX handling. This PR brings several advantages to the user:

• faster page loading times through build time rendering
• Autoactivation works in all cases now, also with inline formulae. Activation and configuration were dropped completely from the configuration file, everything is done behind the scenes now.
• mhchem extension is included in Hugo's embedded KaTeX engine as of v.0.144.0. No need for activation or configuration of mhchem extension inside the config file any more.

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Preview: https://deploy-preview-2276--docsydocs.netlify.app/docs/adding-content/diagrams-and-formulae/

[Copilot]

Pull Request Overview

This PR simplifies KaTeX handling by dropping the client‐side JavaScript files in favor of Hugo’s embedded, server‐side rendering engine, which improves performance and reduces configuration complexity.

• Removed manual activation and configuration instructions from documentation
• Eliminated JS script loading for KaTeX and its auto-render/mhchem extensions
• Updated render templates for math and chemical code blocks to use transform.ToMath

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
userguide/content/en/docs/adding-content/diagrams-and-formulae/index.md	Documentation updated to reflect server-side rendering and removal of manual activation.
layouts/_partials/scripts/katex.html	Removed JS loading for KaTeX, now only loads stylesheet since rendering is done server side.
layouts/_partials/scripts.html	Updated condition to load the KaTeX partial based on server-rendering flags.
layouts/_markup/render-passthrough.html	Updated to use transform.ToMath for math rendering.
layouts/_markup/render-codeblock-math.html	Simplified math block rendering using transform.ToMath.
layouts/_markup/render-codeblock-chem.html	Simplified chemical rendering using transform.ToMath.
CHANGELOG.md	Changelog updated to explain the new server side rendering behavior.

[chalin]

Great news about the simplification! Thanks.

Could you update the PR (including the title) to say that this is build-time rendering, not server-side.

In terms of code style for this repo, please favor tail-end whitespace globing using -}} and drop the {{- when it is unnecessary -- which is most of the time. Thanks.

I'll take a closer review as soon as I can.

[deining]

Great news about the simplification! Thanks.

You are welcome!

Could you update the PR (including the title) to say that this is build-time rendering, not server-side.

Done.

In terms of code style for this repo, please favor tail-end whitespace globing using -}} and drop the {{- when it is unnecessary -- which is most of the time. Thanks.

Changed as requested.

I'll take a closer review as soon as I can.

Looking forward receiving your review soon!

[deining]

Thanks for your thorough review, all changes are incorporated, checkers are green.
While working on the review, I realized that the KaTex stylesheet helds several references to KateX font files. Since we are storing the stylesheet locally now, all these links were broken. This is corrected with this PR now, I'm downloading not only the css file but also the font files at build time now.
I realized that this defect is present in recently released version 12.0 too. I think this defect should be fixed there. We can either backport my changes into v12.0 or we make a new release v12.1 which helds my solution submitted with this PR. Sorry for the inconvenience.
@chalin: WDYT?

[chalin]

Thanks for your thorough review, all changes are incorporated, checkers are green.

Great!

Will get back to you as soon as I can for the next round of review.

[wlbksy]

Marvelous

[chalin]

We can either backport my changes into v12.0 or we make a new release v12.1

We'll be putting out a new release (0.13.0) soon.

[chalin]

Rebased. Overall LGTM