[SlavaKatiukha]

Replace MkDocs with Hugo and the shared Virtuozzo documentation theme. Keep the current docs and all 24 published versions, including existing URLs, images, redirects, and code examples.

Changes:

• Move current articles to content/. Add sidebar section links, version menus, search, code copying, and page feedback.
• Use Devbox, Task, and uv for setup, previews, builds, and Python dependencies.
• Add versioned builds, validation, and manual staging and production workflows.
• Remove the old MkDocs tools, theme, and unused files. Update the contributor and deployment guides.

Validation:

• task build
• task hugo:verify
• All 234 Python tests passed on case-sensitive storage.

[HlibAntonov]

I was thinking about straight up updating branches that we decide to keep to Hugo using approach in https://github.com/virtuozzo/cloudscripting-docs/tree/poc/hugo-migration as a template (it is a simple conversion according to AI). It uses current theme native shortcodes not custom ones, updates old product names and links, fix broken links, applies other editorial and some structural changes.
However, if we agree that it is ok to freeze existing versions as is (with all their problems) and that no further edits will be made on these versions, then conversion is not needed. In any case, future versions should be on Hugo so the template can still be used to create the next CS docs version. It will probably be a bit different from older versions, but will give access to our Hugo tools and simplify any further edits.