refactor(website): keep page text when a script message is missing

A page that omits a message attribute (a translation that drops one, or a
page without the shared footer) must not show empty or "undefined" text:

- Copy buttons still copy without #copy-status or its messages, keep their
  own label and leave the status empty.
- The star label is skipped when the header has no label for the count.
- The percent demo, dinosaur game and speed check leave the current text in
  place for a missing message; an unknown {placeholder} stays literal.

scripts/test-website-scripts.mjs runs main.js, home.js and dino-demo.js
against a small document model with node:test. `website.py check` runs it,
so the website CI job and the publisher's preparation job now set up the
repository's Node.js version.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

.github/workflows/website-check.yml

@@ -30,5 +30,9 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends -y libcairo2 fonts-dejavu-core
           python3 -m pip install -r website/requirements.txt
+      - name: Set up Node.js for website script tests
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: .nvmrc
       - name: Check shared HTML, links, assets and contributor workflows
         run: python3 scripts/website.py check

.github/workflows/website-pages.yml

@@ -59,6 +59,10 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends -y libcairo2 fonts-dejavu-core
           python3 -m pip install -r website/requirements.txt
+      - name: Set up Node.js for website script tests
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: .nvmrc
       - name: Check shared HTML, links, assets and contributor workflows
         run: python3 scripts/website.py check
       - name: Record the published commit