Switch from MkDocs to Zensical

[leMaik]

See https://squidfunk.github.io/mkdocs-material/blog/2025/11/05/zensical/ for more information; i.e. MkDocs seems to be unmaintained and Material for MkDocs is in maintenance mode, Zensical is the successor.

[jackjt8]

The only concern I can see is the plugin/module support.

We're working on shipping essential functionality as provided by MkDocs plugins as built-in modules.

In early 2026, we will open the module system to third-party developers, ...

Which implies that some plugins may need to be dropped until an alternative can be found or created. However, given the timeline/Phased transition strategy they are aiming to reach Phase 2 and 3 in the next 12 months so hopefully by then the majority of plugins we need are transitioned or alternatives can be found.

[leMaik]

We could either wait until phase 1b is completed or check if our plugin use-cases are solved differently in Zensical.
For example, we use the hooks plugin to conditionally exclude pages from the 2.4/2.5 docs, I'm not sure how to achieve that without the plugin (without deleting the files before building the page).