fix(cicd): switch act runner to Docker mode with node:20 image

Host mode lacks Node.js so actions/checkout@v4 fails. Switch label to
ubuntu-latest:docker:node:20 which has Node.js for JS actions. Install
Docker CLI in the deploy job since node:20 doesn't include it.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/deploy.yaml

@@ -23,6 +23,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Install Docker CLI
+        run: apt-get update -qq && apt-get install -y -qq docker.io
+
       - name: Login to Gitea registry
         run: |
           echo "${{ secrets.REGISTRY_PASSWORD }}" \

infrastructure/terraform/act-runner.tf

@@ -106,7 +106,7 @@ resource "kubernetes_deployment" "act_runner" {
                 --instance http://gitea-http.gitea.svc.cluster.local:3000 \
                 --token "$(cat /etc/runner-token/token)" \
                 --name "k3d-runner-$(hostname)" \
-                --labels ubuntu-latest
+                --labels ubuntu-latest:docker:node:20
             fi
             exec act_runner daemon --config /etc/act-runner/config.yaml
           EOT