ci: install docker CLI in deploy job

The node:22-bookworm runner image mounts the Docker socket but lacks the
docker client binary; install the static client before build/run steps.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.forgejo/workflows/deploy.yml

@@ -15,6 +15,17 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      # The `node:22-bookworm` job image has the Docker socket mounted but not
+      # the docker CLI. Install just the static client binary so `docker ...`
+      # commands can talk to the host's Docker daemon.
+      - name: Install Docker CLI
+        run: |
+          if ! command -v docker >/dev/null 2>&1; then
+            curl -fsSL https://download.docker.com/linux/static/stable/x86_64/docker-27.3.1.tgz \
+              | tar -xz -C /usr/local/bin --strip-components=1 docker/docker
+          fi
+          docker version
+
       # Build the site into an nginx image (see Dockerfile). Tagged with the
       # commit SHA for traceability, plus :latest for convenience.
       - name: Build image