feat: add gitea pages deployment

.gitea/workflows/publish-site.yml

@@ -0,0 +1,45 @@
+name: Build and Publish Gitea Pages
+
+on:
+  push:
+    branches:
+      # Switch to main after testing the deployment.
+      - feature/gitea_pages
+  workflow_dispatch:
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest-intranet
+    container:
+      image: gitea.psi.ch/images/alpine-zensical
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Build site
+        env:
+          PAGES_URL: https://${{ github.repository_owner }}.pages.psi.ch/${{ github.event.repository.name }}/
+        run: |
+          # Use the Pages URL for this build while retaining the Read the Docs config.
+          sed "s|^site_url = .*|site_url = \"${PAGES_URL}\"|" \
+            zensical.toml > zensical.pages.toml
+          /opt/python-env/bin/zensical build --clean --config-file zensical.pages.toml
+
+      - name: Publish to gitea-pages
+        env:
+          PAGES_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PAGES_REPOSITORY: ${{ github.repository }}
+        run: |
+          # Create a separate repository containing only generated files,
+          # including hidden files, so source files cannot enter the Pages branch.
+          publish_dir=$(mktemp -d)
+          cp -a site/. "$publish_dir/"
+          cd "$publish_dir"
+          git init
+          git config user.name "Gitea Actions"
+          git config user.email "actions@gitea.local"
+          git add .
+          git commit -m "Update site - $(date -u)"
+          git push --force \
+            "https://${PAGES_TOKEN}@gitea.psi.ch/${PAGES_REPOSITORY}.git" \
+            HEAD:gitea-pages