Switch site to Docusaurus

- 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

.github/workflows/ci.yml

@@ -6,14 +6,13 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+        with:
+          node-version: 20
+          cache: yarn
 
-    - uses: ammaraskar/sphinx-action@master
-      with:
-        docs-folder: "docs/"
-        build-command: "sphinx-build -nW -b html source/ build/html/"
-
-    - uses: actions/upload-artifact@v1
-      with:
-        name: ethdebug-format-html
-        path: docs/build/html/
+      - name: Install dependencies
+        run: yarn install --frozen-lockfile
+      - name: Build website
+        run: yarn build

.github/workflows/gh-pages.yml

@@ -7,18 +7,29 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/setup-python@v2
-      - uses: actions/checkout@master
-        with:
-          fetch-depth: 0 # otherwise, you will failed to push refs to dest repo
-      - name: Build and Commit
-        uses: sphinx-notes/pages@v2
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-node@v3
         with:
-          documentation_path: "./docs/source"
-          requirements_path: "./docs/requirements.txt"
+          node-version: 20
+          cache: yarn
+
+      - name: Install dependencies
+        run: yarn install --frozen-lockfile
+        working-directory: ./web
+
+      - name: Build website
+        run: yarn build
+        working-directory: ./web
 
-      - name: Push changes
-        uses: ad-m/github-push-action@master
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
-          branch: gh-pages
+
+          publish_dir: ./web/build
+
+          # default deployer
+          user_name: 'github-actions[bot]'
+          user_email: 'github-actions[bot]@users.noreply.github.com'
+