ci: add buildkit_config docker.io mirror to fix base image pull

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.woodpecker.yml

@@ -24,6 +24,10 @@ steps:
       dockerfile: ./Dockerfile
       platforms: linux/amd64
       mirror: https://5c492fmo.mirror.aliyuncs.com
+      # 给 buildkit 构建容器配 docker.io 镜像加速(mirror 只作用于 dockerd, 不作用于 buildkit)
+      buildkit_config: |
+        [registry."docker.io"]
+          mirrors = ["5c492fmo.mirror.aliyuncs.com", "docker.m.daocloud.io"]
       # 注册表层缓存: requirements 未变时直接命中, 重建很快
       cache_images:
         - registry.woni.link/woni/office-xbot-feishu:cache