fix: install Docker CLI in CI step before docker-compose build

Each CI step runs in a separate container (node:18-bullseye).
Docker CLI must be installed within that container to use docker-compose.

.gitea/workflows/ci.yml

@@ -61,5 +61,14 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
+      - name: Install Docker CLI
+        run: |
+          curl -fsSL https://download.docker.com/linux/static/stable/x86_64/docker-24.0.7.tgz -o /tmp/docker.tgz
+          tar -xzf /tmp/docker.tgz -C /tmp
+          cp /tmp/docker/docker /usr/local/bin/
+          chmod +x /usr/local/bin/docker
+          curl -fsSL "https://github.com/docker/compose/releases/latest/download/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
+          chmod +x /usr/local/bin/docker-compose
+
       - name: Build Docker images
         run: docker-compose build