feat: 新增 Docker 容器化部署，支持 Docker Hub 镜像发布

多阶段 Dockerfile、Compose、/health 探活与 JIANG13_* 环境变量；
entrypoint 自动修正 /data 卷权限，适配 1Panel 等平台；更新 README 部署文档。

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/docker.yml

@@ -0,0 +1,58 @@
+# 构建并推送 Docker 镜像到 Docker Hub
+# 前置条件：在 GitHub 仓库 Secrets 中配置
+#   DOCKERHUB_USERNAME — Docker Hub 用户名
+#   DOCKERHUB_TOKEN    — Docker Hub Access Token（需 Read & Write 权限）
+
+name: Docker
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+
+env:
+  IMAGE_NAME: hangzhang714128/jiang13-forum
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: 计算镜像标签与版本
+        id: meta
+        run: |
+          IMAGE="${{ env.IMAGE_NAME }}"
+          TAGS="${IMAGE}:latest"
+          if [[ "${{ github.ref_type }}" == "tag" ]]; then
+            RAW="${GITHUB_REF#refs/tags/}"
+            VER="${RAW#v}"
+            TAGS="${TAGS},${IMAGE}:${VER},${IMAGE}:${RAW}"
+            echo "version=${VER}" >> "$GITHUB_OUTPUT"
+          else
+            SHA="${GITHUB_SHA::7}"
+            TAGS="${TAGS},${IMAGE}:sha-${SHA}"
+            echo "version=dev" >> "$GITHUB_OUTPUT"
+          fi
+          echo "tags=${TAGS}" >> "$GITHUB_OUTPUT"
+
+      - name: 登录 Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: 构建并推送镜像
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          platforms: linux/amd64
+          build-args: |
+            VERSION=${{ steps.meta.outputs.version }}
+            IMAGE_PREFIX=
+          tags: ${{ steps.meta.outputs.tags }}