Smaller docs website

[myrrc]

Change docs.vortex.dev website:

1. Remove Doxygen, C++ reference doesn't use it currently
2. Use literal includes for C++ examples so that they automatically
   change once .cpp file changes
3. Remove all JS from pages except for search page.
4. Rewrite TOC section so that it opens without JS (detail/summary).
5. Use own theme with colors from vortex.dev.
6. Remove unused dependencies from UV.
7. Manually write references.md instead of using bibtex.
8. Remove icon fonts
9. Change dark/light theme without JS (prefers-color-scheme).
10. Use syntax highlighting without JS (pygments).