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/src/components/HomepageFeatures/index.tsx

@@ -0,0 +1,84 @@
+import type {ReactNode} from 'react';
+import clsx from 'clsx';
+import Heading from '@theme/Heading';
+import Translate from '@docusaurus/Translate';
+import styles from './styles.module.css';
+
+type FeatureItem = {
+  title: ReactNode;
+  description: ReactNode;
+};
+
+const FEATURES: FeatureItem[] = [
+  {
+    title: <Translate id="feat.types.title">Many Backup Types</Translate>,
+    description: (
+      <Translate id="feat.types.desc">
+        Files &amp; directories with multi-path sources, plus MySQL, PostgreSQL, SQLite, and SAP HANA — all in one place.
+      </Translate>
+    ),
+  },
+  {
+    title: <Translate id="feat.storage.title">70+ Storage Backends</Translate>,
+    description: (
+      <Translate id="feat.storage.desc">
+        Native Alibaba OSS, Tencent COS, Qiniu, S3, Google Drive, WebDAV, FTP — plus SFTP, Azure Blob, Dropbox, OneDrive and dozens more via rclone.
+      </Translate>
+    ),
+  },
+  {
+    title: <Translate id="feat.scheduling.title">Scheduling &amp; Retention</Translate>,
+    description: (
+      <Translate id="feat.scheduling.desc">
+        Cron-based schedules with a visual editor and auto-retention (by days or count), plus empty-directory cleanup.
+      </Translate>
+    ),
+  },
+  {
+    title: <Translate id="feat.cluster.title">Multi-Node Cluster</Translate>,
+    description: (
+      <Translate id="feat.cluster.desc">
+        Master-Agent mode manages backups across multiple servers. Agents run tasks locally and upload straight to storage — no reverse connectivity required.
+      </Translate>
+    ),
+  },
+  {
+    title: <Translate id="feat.security.title">Secure by Default</Translate>,
+    description: (
+      <Translate id="feat.security.desc">
+        JWT auth, bcrypt passwords, AES-256-GCM encrypted config, optional backup encryption, and a full audit log.
+      </Translate>
+    ),
+  },
+  {
+    title: <Translate id="feat.deploy.title">Painless Deployment</Translate>,
+    description: (
+      <Translate id="feat.deploy.desc">
+        Single static binary with embedded SQLite. Docker one-click or bare-metal via install.sh — zero external dependencies.
+      </Translate>
+    ),
+  },
+];
+
+function Feature({title, description}: FeatureItem) {
+  return (
+    <div className={clsx('col col--4', styles.feature)}>
+      <Heading as="h3">{title}</Heading>
+      <p>{description}</p>
+    </div>
+  );
+}
+
+export default function HomepageFeatures(): ReactNode {
+  return (
+    <section className={styles.features}>
+      <div className="container">
+        <div className="row">
+          {FEATURES.map((props, idx) => (
+            <Feature key={idx} {...props} />
+          ))}
+        </div>
+      </div>
+    </section>
+  );
+}

docs-site/src/components/HomepageFeatures/styles.module.css

@@ -0,0 +1,20 @@
+.features {
+  display: flex;
+  align-items: center;
+  padding: 3rem 0;
+  width: 100%;
+}
+
+.feature {
+  padding: 1.2rem 1rem;
+}
+
+.feature h3 {
+  font-size: 1.15rem;
+  margin-bottom: 0.5rem;
+}
+
+.feature p {
+  color: var(--ifm-color-content-secondary);
+  line-height: 1.65;
+}