Automate website push to LRZ GItLab (#12)

* Use SSH action workflow

* Add SSH connection check

* Add SSH known hosts

* Set up push as separate job and push all branches

* Add the forgotten checkout step

* Force push gh-pages to lrz remote

* Explicitly checkout gh-pages branch and add checks

.github/workflows/publish.yml

@@ -22,4 +22,51 @@ jobs:
         with:
           target: gh-pages
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  push-to-lrz-gitlab:
+    needs: build-deploy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up SSH
+        uses: webfactory/[email protected]
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
+
+      - name: Add GitLab to known hosts
+        run: |
+          mkdir -p ~/.ssh
+          ssh-keyscan gitlab.lrz.de >> ~/.ssh/known_hosts
+          # You can also verify the fingerprint manually (optional)
+          # ssh-keyscan gitlab.lrz.de | tee -a ~/.ssh/known_hosts
+          
+      - name: Check LRZ connection
+        run: |
+          ssh -T [email protected]
+          
+      - name: Add LRZ GitLab remote
+        run: |
+          git remote add lrz_gitlab_remote [email protected]:lmu-open-science-center/lmu-osc-website.git
+          git remote -v
+          
+      - name: Fetch and checkout branch
+        run: |
+          git status
+          git branch
+          git fetch origin gh-pages
+          git branch
+          git checkout -b gh-pages origin/gh-pages
+          git branch
+          git status
+        
+      - name: Push gh-pages to LRZ
+        run: |
+          # push gh-pages
+          git push --force lrz_gitlab_remote gh-pages
+        
+