- Remove Sphinx stuff

- Prepare formal schema by starting a `schema/` directory with some
  rough sketches

- Setup Docusaurus within `web/` directory:

  - Initialize Docusaurus and remove all the default stuff
    (logos, blog, etc.)

  - Establish `docs/` subdirectory for human-readable content about
    ethdebug, our efforts, etc.

  - Establish `spec/` subdirectory for direct specification materials,
    using Docusaurus's mechanism for keeping two "docs" directories.

  - Author basic homepage so ethdebug has a proper home on the web

  - Define initial version of function for loading schemas from root
    `schema/` directory, and reference this schema in the `spec/`
    subdirectory.

  - Extend theme to provide access to FontAwesome for icons

  - Extend theme to include "external link" badge on external links in
    Markdown files

  - Include a temporary logo generated by ChatGPT

  - Override default colors with temporary colorscheme suggested by ChatGPT

- Update GitHub Actions workflows for new toolchain