Change cron schedule to 00:00 on the 1st of each month

Updated the cron schedule for monthly builds.
每月1号0点构建镜像 (utc+8)

Author: kanao7

.github/workflows/docker-build.yml

@@ -0,0 +1,47 @@
+name: Build Caddy Cloudflare Latest
+
+on:
+  push:
+    branches: ["main"]
+  schedule:
+    - cron: '0 16 1 * *' # 每月1号自动构建一次，确保镜像保持最新
+  workflow_dispatch:      # 允许手动点击按钮触发构建
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          # 自动编译兼容普通服务器(amd64)和ARM服务器(arm64)
+          platforms: linux/amd64,linux/arm64
+          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=max