Bind GitHub Pages deployment to custom domain eupago.bilouro.com

Project sites on bilouro.github.io/* are systematically rejected by
Google Search Console's sitemap fetcher — documented across multiple
threads (squidfunk/mkdocs-material#7478, GitHub community#149884) as
caused by crawl-budget penalties on the shared github.io subdomain.
Custom domain bypasses the issue: confirmed by multiple users in those
threads.

Adds the CNAME file at build time + sets the custom domain on the
Pages settings via the API. SSL provisions automatically (~30 min).

Author: bilouro

.github/workflows/docs.yml

@@ -38,6 +38,11 @@ jobs:
       # reads the sitemap through Jekyll's wrapper and GSC reports
       # "Couldn't fetch" even though the file is served correctly.
       - run: touch site/.nojekyll
+      # CNAME for the custom domain — GitHub Pages reads this file at the
+      # site root to bind the deployment to the configured custom domain.
+      # Solves the GSC "Couldn't fetch sitemap" problem inherent to project
+      # sites under github.io (shared subdomain, crawl-budget penalties).
+      - run: echo "eupago.bilouro.com" > site/CNAME
       - uses: actions/upload-pages-artifact@v3
         with:
           path: site