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/development/setup.md

@@ -0,0 +1,83 @@
+---
+sidebar_position: 1
+title: Development Setup
+description: Get a BackupX dev environment running — backend, frontend, tests.
+---
+
+# Development Setup
+
+**Requirements:** Go ≥ 1.25, Node.js ≥ 20, npm.
+
+## Clone & install
+
+```bash
+git clone https://github.com/Awuqing/BackupX.git && cd BackupX
+cd web && npm install && cd ..
+```
+
+## Dev servers
+
+Run the backend and the Vite dev server in two terminals:
+
+```bash
+# Terminal 1: backend on :8340
+make dev-server
+
+# Terminal 2: Vite with HMR on :5173
+make dev-web
+```
+
+The Vite config proxies `/api` to `http://127.0.0.1:8340` so you can open the UI at `http://localhost:5173`.
+
+## Tests
+
+```bash
+make test           # runs Go + Web test suites
+make test-server    # Go only
+make test-web       # Vitest only
+```
+
+## Production build
+
+```bash
+make build          # server/bin/backupx + web/dist
+make docker         # Docker image
+make docker-cn      # Docker image with mainland China mirrors
+```
+
+## Tech stack
+
+| Component | Stack |
+|-----------|-------|
+| **Backend** | Go · Gin · GORM · SQLite · robfig/cron · rclone |
+| **Frontend** | React 18 · TypeScript · ArcoDesign · Vite · Zustand · ECharts |
+| **Storage** | rclone (70+ backends) · AWS SDK v2 · Google Drive API v3 |
+| **Security** | JWT · bcrypt · AES-256-GCM |
+
+## Project layout
+
+```
+BackupX/
+├── server/             # Go backend
+│   ├── cmd/backupx/    # Entry point + subcommands (agent, backint, reset-password)
+│   ├── internal/
+│   │   ├── agent/      # Agent CLI logic
+│   │   ├── app/        # Wiring (repositories → services → handlers)
+│   │   ├── backup/     # Backup runners (file / mysql / postgres / sqlite / saphana)
+│   │   ├── backint/    # SAP HANA Backint protocol
+│   │   ├── http/       # HTTP handlers + router
+│   │   ├── model/      # GORM models
+│   │   ├── repository/ # DB access
+│   │   ├── service/    # Business logic
+│   │   └── storage/    # Storage providers (rclone + direct SDKs)
+│   └── pkg/            # Generic utilities
+├── web/                # React frontend (Vite)
+│   └── src/
+│       ├── components/
+│       ├── pages/
+│       ├── services/
+│       └── types/
+├── docs-site/          # This documentation site (Docusaurus)
+├── deploy/             # install.sh, systemd unit, nginx config
+└── Makefile
+```