Switch GitHub Pages to Jekyll build for markdown rendering

The static deployment served raw .md files, causing 404s on protocol
doc links (which point to .html). Jekyll processes the .md files with
their front matter (layout: default) into proper HTML pages.

.github/workflows/static.yml

@@ -1,43 +1,43 @@
-# Simple workflow for deploying static content to GitHub Pages
-name: Deploy static content to Pages
+# Build and deploy Jekyll site to GitHub Pages
+name: Deploy to Pages
 
 on:
-  # Runs on pushes targeting the default branch
   push:
     branches: ["main"]
-
-  # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
 
-# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
 permissions:
   contents: read
   pages: write
   id-token: write
 
-# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
-# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
 concurrency:
   group: "pages"
   cancel-in-progress: false
 
 jobs:
-  # Single deploy job since we're just deploying
-  deploy:
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
+  build:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Setup Pages
         uses: actions/configure-pages@v5
+      - name: Build with Jekyll
+        uses: actions/jekyll-build-pages@v1
+        with:
+          source: ./docs
+          destination: ./_site
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v3
-        with:
-          # Upload docs directory as site root
-          path: 'docs'
+
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
       - name: Deploy to GitHub Pages
         id: deployment
         uses: actions/deploy-pages@v4