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/getting-started/installation.md

@@ -0,0 +1,82 @@
+---
+sidebar_position: 1
+title: Installation
+description: Install BackupX via Docker, prebuilt archive, or from source.
+---
+
+# Installation
+
+BackupX ships as a single static binary. Three ways to install, pick the one that matches your environment.
+
+## Docker (recommended)
+
+No cloning required.
+
+```bash
+docker run -d --name backupx \
+  -p 8340:8340 \
+  -v backupx-data:/app/data \
+  awuqing/backupx:latest
+```
+
+Or use `docker compose`:
+
+```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 to back up (as needed):
+      # - /var/www:/mnt/www:ro
+      # - /etc/nginx:/mnt/nginx-conf:ro
+    environment:
+      - TZ=Asia/Shanghai
+
+volumes:
+  backupx-data:
+```
+
+Images: [`awuqing/backupx`](https://hub.docker.com/r/awuqing/backupx) — supports `linux/amd64` and `linux/arm64`.
+
+## Prebuilt archive (bare metal)
+
+Download from the [Releases page](https://github.com/Awuqing/BackupX/releases) and run the installer:
+
+```bash
+tar xzf backupx-v*-linux-amd64.tar.gz && cd backupx-*
+sudo ./install.sh        # creates system user, installs to /opt/backupx, sets up systemd + nginx
+```
+
+The installer:
+
+1. Creates a `backupx` system user
+2. Installs binary to `/opt/backupx/backupx`
+3. Creates `/opt/backupx/config.yaml` with safe defaults
+4. Installs and enables the `backupx.service` systemd unit
+5. (Optional) Configures an Nginx reverse proxy
+
+## From source
+
+Requires Go ≥ 1.25 and Node.js ≥ 20.
+
+```bash
+git clone https://github.com/Awuqing/BackupX.git && cd BackupX
+make build
+# or, for builds behind the great firewall
+make docker-cn
+```
+
+After `make build`, the binary is at `server/bin/backupx` and the built web UI is at `web/dist/`.
+
+## Verify the install
+
+```bash
+backupx --version           # e.g. v1.6.0
+```
+
+Then open `http://your-server:8340` to see the initial admin setup screen.