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/bare-metal.md

@@ -0,0 +1,86 @@
+---
+sidebar_position: 2
+title: Bare-metal Deployment
+description: systemd + Nginx deployment from the prebuilt release tarball or source.
+---
+
+# Bare-metal Deployment
+
+## From prebuilt release
+
+```bash
+# Download the matching tarball
+curl -LO https://github.com/Awuqing/BackupX/releases/latest/download/backupx-v1.6.0-linux-amd64.tar.gz
+
+# Extract and install
+tar xzf backupx-v*-linux-amd64.tar.gz && cd backupx-*
+sudo ./install.sh
+```
+
+The installer performs these steps automatically:
+
+1. Creates a system user `backupx`
+2. Copies the binary to `/opt/backupx/`
+3. Generates a default `config.yaml` with safe JWT/encryption secrets
+4. Installs `backupx.service` (systemd), enabled at boot
+5. (Optional) installs an Nginx site file — see [Nginx Reverse Proxy](./nginx)
+
+## From source
+
+```bash
+git clone https://github.com/Awuqing/BackupX.git && cd BackupX
+make build
+sudo ./deploy/install.sh
+```
+
+`make build` compiles:
+
+- `server/bin/backupx` (Go backend, no CGO)
+- `web/dist/` (React frontend, `npm run build`)
+
+## systemd
+
+The installed unit:
+
+```ini title="/etc/systemd/system/backupx.service"
+[Unit]
+Description=BackupX backup management service
+After=network.target
+
+[Service]
+Type=simple
+User=backupx
+WorkingDirectory=/opt/backupx
+ExecStart=/opt/backupx/backupx --config /opt/backupx/config.yaml
+Restart=on-failure
+RestartSec=5s
+LimitNOFILE=65536
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Typical operations:
+
+```bash
+sudo systemctl status backupx
+sudo journalctl -u backupx -f    # live logs
+sudo systemctl restart backupx
+```
+
+## Password reset
+
+If the admin password is lost:
+
+```bash
+/opt/backupx/backupx reset-password \
+  --username admin \
+  --password 'newpass123' \
+  --config /opt/backupx/config.yaml
+```
+
+Docker equivalent:
+
+```bash
+docker exec -it backupx /app/bin/backupx reset-password --username admin --password 'newpass123'
+```