Add accessilbilty check and fixes

.forgejo/workflows/deploy.yaml

@@ -78,3 +78,26 @@ jobs:
         with:
           name: website-build
           path: public/
+
+  # Separate from the build, so that accessibility findings show up on PRs without blocking deploys.
+  accessibility:
+    runs-on: docker
+    container:
+      image: docker.io/hugomods/hugo:0.165.0
+    steps:
+      - name: Install packages
+        run: |
+          apk update
+          # For CI actions and pa11y.
+          apk add nodejs-current npm
+          # For website build.
+          apk add tzdata git
+          # For pa11y: a browser, fonts for it, and a web server for the built site.
+          apk add chromium font-dejavu python3
+
+      - uses: actions/checkout@v7
+        with:
+          submodules: recursive
+
+      - name: Check accessibility with pa11y
+        run: ./scripts/pa11y.sh