Transition from (Material for) MkDocs to Zensical #10

The Material for MkDocs team is stopping support for its site generator because MkDocs is unmaintained since 2024 (supply chain risk). https://squidfunk.github.io/mkdocs-material/changelog/#9.7.0

The Material for MkDocs team created Zensical, their own static site generator written in Rust and Python. It should be largely compatible.