ci: add deploy workflow for the k3s test cluster

im_workbench had no CI/CD before. Build+push under the mutable
:test tag the cluster overlay tracks, then roll the k3s deployment.

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

.gitea/workflows/deploy.yml

@@ -0,0 +1,37 @@
+name: Deploy im-workbench (k3s test cluster)
+
+on:
+  workflow_dispatch:
+    inputs:
+      image_tag:
+        description: '镜像tag，默认为 test（与集群 kustomization 里的 newTag 一致）'
+        required: false
+
+jobs:
+  deploy:
+    runs-on: deploy-host
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: 确定镜像tag
+        id: vars
+        run: |
+          TAG="${{ github.event.inputs.image_tag }}"
+          [ -z "$TAG" ] && TAG=test
+          echo "tag=$TAG" >> "$GITHUB_OUTPUT"
+
+      - name: 登录镜像仓库
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login git.118im.com -u admin --password-stdin
+
+      - name: 构建并推送镜像
+        run: |
+          docker build -t git.118im.com/im_team/im-workbench:${{ steps.vars.outputs.tag }} .
+          docker push git.118im.com/im_team/im-workbench:${{ steps.vars.outputs.tag }}
+
+      - name: 部署到k3s测试集群
+        run: |
+          mkdir -p ~/.kube
+          echo "${{ secrets.KUBECONFIG }}" > ~/.kube/config
+          chmod 600 ~/.kube/config
+          kubectl rollout restart deployment/im-workbench -n workbench-system
+          kubectl rollout status deployment/im-workbench -n workbench-system --timeout=120s