ci: publikace webu na gh-pages přes Gitea Actions

Při pushi do main se vyrenderuje Quarto web a obsah _site/
se překlopí do větve gh-pages (historie větve zůstává zachována).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitea/workflows/publish.yml

@@ -0,0 +1,63 @@
+name: Publish site
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+env:
+  QUARTO_VERSION: "1.10.18"
+
+jobs:
+  build-deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Quarto
+        run: |
+          set -e
+          curl -sSL -o /tmp/quarto.tar.gz \
+            "https://github.com/quarto-dev/quarto-cli/releases/download/v${QUARTO_VERSION}/quarto-${QUARTO_VERSION}-linux-amd64.tar.gz"
+          mkdir -p "$HOME/opt"
+          tar -xzf /tmp/quarto.tar.gz -C "$HOME/opt"
+          echo "$HOME/opt/quarto-${QUARTO_VERSION}/bin" >> "$GITHUB_PATH"
+
+      - name: Render
+        run: quarto render
+
+      - name: Deploy to gh-pages
+        env:
+          TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: |
+          set -e
+          REMOTE="https://x-access-token:${TOKEN}@gitea.spacilovi.eu/${GITHUB_REPOSITORY}.git"
+
+          git config --global user.name "gitea-actions"
+          git config --global user.email "gitea-actions@spacilovi.eu"
+
+          # pracovní kopie gh-pages (zachová dosavadní historii větve)
+          if git ls-remote --exit-code "$REMOTE" gh-pages >/dev/null 2>&1; then
+            git fetch "$REMOTE" gh-pages
+            git worktree add /tmp/gh-pages FETCH_HEAD
+            cd /tmp/gh-pages
+            git checkout -B gh-pages
+          else
+            mkdir -p /tmp/gh-pages
+            cd /tmp/gh-pages
+            git init -q -b gh-pages
+          fi
+
+          # zahodit staré soubory (kromě .git) a nakopírovat nový build
+          find . -mindepth 1 -maxdepth 1 ! -name .git -exec rm -rf {} +
+          cp -a "${GITHUB_WORKSPACE}/_site/." .
+          touch .nojekyll
+
+          git add -A
+          if git diff --cached --quiet; then
+            echo "Beze změn, nic se nepublikuje."
+            exit 0
+          fi
+          git commit -q -m "Built site for gh-pages (${GITHUB_SHA::7})"
+          git push "$REMOTE" HEAD:gh-pages