Migrate from MkDocs to Zensical

Material for MkDocs developer deprecated the project for several reasons which can be read in the post below. As a replacement, he started Zensical which should be compatible with Mkdocs and its plug-ins.

• https://squidfunk.github.io/mkdocs-material/blog/2025/11/05/zensical/
• https://zensical.org/compatibility/#phased-transition-strategy

Give it a try time to time to see the progress (currently alpha, when it reaches beta, stable) on how compatible how our configuration is compatible.