文档: 新增 Docusaurus 官网与双语文档，README 切换为英文默认 (#39)

- 新建 docs-site/ Docusaurus 项目，支持 en + zh-Hans 双语
- 从 README 迁移内容为独立文档页面：
  - Getting Started（安装、快速开始）
  - Deployment（Docker、裸机、Nginx、配置参考）
  - Features（备份类型、存储后端、SAP HANA、多节点集群、通知）
  - Reference（API、CLI）
  - Development（开发、贡献）
- 自定义 BackupX 主题色、logo、落地页组件
- 新增 .github/workflows/docs.yml，Actions 自动构建并发布到 GitHub Pages
- README.md 切换为英文，中文版挪到 README.zh-CN.md，两者均精简为导航型
- 配置站点 URL：https://awuqing.github.io/BackupX/

docs-site/docs/deployment/docker.md

@@ -0,0 +1,68 @@
+---
+sidebar_position: 1
+title: Docker Deployment
+description: Production-style Docker deployment with docker compose, mounted source directories, and environment overrides.
+---
+
+# Docker Deployment
+
+BackupX's official Docker image [`awuqing/backupx`](https://hub.docker.com/r/awuqing/backupx) supports multi-architecture (linux/amd64 + linux/arm64).
+
+## Compose file
+
+```yaml title="docker-compose.yml"
+services:
+  backupx:
+    image: awuqing/backupx:latest
+    container_name: backupx
+    restart: unless-stopped
+    ports:
+      - "8340:8340"
+    volumes:
+      - backupx-data:/app/data
+      # Mount host directories you want to back up:
+      - /var/www:/mnt/www:ro
+      - /etc/nginx:/mnt/nginx-conf:ro
+    environment:
+      - TZ=Asia/Shanghai
+      - BACKUPX_LOG_LEVEL=info
+      - BACKUPX_BACKUP_MAX_CONCURRENT=2
+
+volumes:
+  backupx-data:
+```
+
+Start with:
+
+```bash
+docker compose up -d
+```
+
+## Host-directory backup
+
+To back up files from the host, mount them into the container. When creating a file-type task in the web UI, point the source path at the mount location (e.g. `/mnt/www`). Make sure the directory is visible inside the container.
+
+## Environment variables
+
+All configuration keys can be overridden with the `BACKUPX_` prefix:
+
+```yaml
+environment:
+  - TZ=Asia/Shanghai
+  - BACKUPX_SERVER_PORT=8340
+  - BACKUPX_LOG_LEVEL=debug
+  - BACKUPX_BACKUP_MAX_CONCURRENT=4
+  - BACKUPX_BACKUP_TEMP_DIR=/tmp/backupx
+```
+
+See the [Configuration](./configuration) page for the full list.
+
+## Upgrades
+
+Check **System Settings → Check Updates** in the UI to see if a new version is available, then on the host:
+
+```bash
+docker compose pull && docker compose up -d
+```
+
+No migrations needed — BackupX auto-migrates the SQLite schema on startup.