ci(docs): publish through the shared GitHub Pages workflow (#42)

The workflow was a copy of common-publish-to-github-pages.yml -- same checkout,
Pages config, Node setup, Antora build, artifact upload and deploy -- so any fix
to one had to be remembered in the other.

Two differences, both in the shared workflow's favour:

- it passes --log-failure-level=fatal to Antora, so a fatal is a failed build
  rather than a broken site
- the `mkdir -p docs/build/site` guard is gone. It made an Antora run that
  produced nothing deploy an empty directory instead of failing.

The repo's own package-lock.json still pins Antora: the shared build action runs
`npm ci` when it finds a lockfile and falls back to a pinned install only when
there isn't one.

Signed-off-by: Jimisola Laursen <jimisola@jimisola.com>

Author: jimisola

.github/workflows/publish_gh_pages.yml

@@ -1,47 +1,20 @@
 name: Publish to GitHub Pages
+
 on:
-  workflow_dispatch:  
+  workflow_dispatch:
   release:
     types: [created]
   push:
     branches:
       - main
 
-concurrency:
-  group: github-pages
-  cancel-in-progress: false
-# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
 permissions:
   contents: read
-  pages: write
-  id-token: write
+
 jobs:
-  build:
-    runs-on: ubuntu-latest
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v7
-        with:
-          fetch-depth: 0
-      - name: Configure Pages
-        uses: actions/configure-pages@v6
-      - name: Install Node.js
-        uses: actions/setup-node@v7
-        with:
-          node-version: "24"
-      - name: Install dependencies
-        run: npm ci
-      - name: Generate Site
-        run: npx antora docs/antora-playbook.yml
-      - name: Create site folders
-        run: mkdir -p docs/build/site
-      - name: Upload Artifacts
-        uses: actions/upload-pages-artifact@v5
-        with:
-          path: docs/build/site
-      - name: Deploy to GitHub Pages
-        id: deployment
-        uses: actions/deploy-pages@v5
+  publish:
+    uses: reqstool/.github/.github/workflows/common-publish-to-github-pages.yml@main
+    permissions:
+      contents: read
+      pages: write
+      id-token: write