[Roadmap] Migrate documentation to DocumenterVitepress across all packages

[ocots]

Objective

Migrate all control-toolbox package documentation to DocumenterVitepress.

Context

The migration has already started in CTBase and several other packages. The goal is to have a consistent, modern documentation theme across the entire ecosystem.

Why

Vitepress provides a modern, fast, and clean documentation experience. A consistent theme across all packages improves the user experience and brand identity of the control-toolbox ecosystem. The Handbook already documents the Vitepress setup process.

References

• DocumenterVitepress.jl
• Handbook — Vitepress doc
• Roadmap comment