功能: 系统更新检查（GitHub Release + Docker）

后端：
- 新增 GET /api/system/update-check，从 GitHub Releases API 获取最新版本
- 自动比较当前版本与最新版本，匹配当前平台的下载链接
- 返回版本号、更新说明、下载链接、Docker 镜像信息

前端（系统设置页重构）：
- 新增"检查更新"按钮，点击后展示更新结果
- 有新版本时显示版本号、更新说明、下载按钮、Docker 更新命令
- 新增磁盘状态卡片（总空间/已用/可用/使用率）
- 运行模式用彩色 Tag 区分（生产/开发）

web/src/pages/settings/SettingsPage.tsx

@@ -1,88 +1,137 @@
-import { Card, Descriptions, Grid, PageHeader, Space, Typography } from '@arco-design/web-react'
+import { Badge, Button, Card, Descriptions, Grid, Link, PageHeader, Space, Tag, Typography } from '@arco-design/web-react'
 import { useEffect, useState } from 'react'
-import { fetchSystemInfo, type SystemInfo } from '../../services/system'
+import { fetchSystemInfo, checkUpdate, type SystemInfo, type UpdateCheckResult } from '../../services/system'
 import { resolveErrorMessage } from '../../utils/error'
 import { formatDuration } from '../../utils/format'
 
 const { Row, Col } = Grid
 
-const deploySteps = [
-  '1. 构建前端：cd web && npm run build',
-  '2. 编译后端：cd server && go build -o backupx ./cmd/backupx',
-  '3. 部署静态资源与二进制，并按 deploy/ 目录提供的配置接入 Nginx 与 systemd',
-  '4. 首次启动后访问 Web 控制台，完成管理员初始化与存储目标配置',
-]
+function formatBytes(bytes: number | undefined): string {
+  if (!bytes || bytes <= 0) return '-'
+  const units = ['B', 'KB', 'MB', 'GB', 'TB']
+  let i = 0
+  let size = bytes
+  while (size >= 1024 && i < units.length - 1) {
+    size /= 1024
+    i++
+  }
+  return `${size.toFixed(1)} ${units[i]}`
+}
 
 export function SettingsPage() {
   const [info, setInfo] = useState<SystemInfo | null>(null)
   const [loading, setLoading] = useState(true)
   const [error, setError] = useState('')
+  const [updateResult, setUpdateResult] = useState<UpdateCheckResult | null>(null)
+  const [checking, setChecking] = useState(false)
 
   useEffect(() => {
     let active = true
     void (async () => {
       try {
         const result = await fetchSystemInfo()
-        if (active) {
-          setInfo(result)
-          setError('')
-        }
+        if (active) { setInfo(result); setError('') }
       } catch (loadError) {
-        if (active) {
-          setError(resolveErrorMessage(loadError, '加载系统设置失败'))
-        }
+        if (active) setError(resolveErrorMessage(loadError, '加载系统信息失败'))
       } finally {
-        if (active) {
-          setLoading(false)
-        }
+        if (active) setLoading(false)
       }
     })()
-    return () => {
-      active = false
-    }
+    return () => { active = false }
   }, [])
 
+  async function handleCheckUpdate() {
+    setChecking(true)
+    try {
+      const result = await checkUpdate()
+      setUpdateResult(result)
+    } catch (e) {
+      setUpdateResult({ currentVersion: info?.version || '-', latestVersion: '-', hasUpdate: false, error: resolveErrorMessage(e, '检查更新失败') })
+    } finally {
+      setChecking(false)
+    }
+  }
+
   return (
     <Space direction="vertical" size="large" style={{ width: '100%' }}>
-      <PageHeader
-        style={{ paddingBottom: 16 }}
-        title="系统设置"
-        subTitle="展示当前运行信息、部署入口和交付所需的基础操作说明"
-      >
+      <PageHeader style={{ paddingBottom: 16 }} title="系统设置" subTitle="运行信息、磁盘状态与版本更新">
         {error ? <Typography.Text type="error">{error}</Typography.Text> : null}
       </PageHeader>
 
       <Row gutter={16}>
         <Col span={12}>
           <Card loading={loading} title="运行信息">
-            <Descriptions
-              column={1}
-              border
-              data={[
-                { label: '版本', value: info?.version ?? '-' },
-                { label: '运行模式', value: info?.mode ?? '-' },
-                { label: '运行时长', value: formatDuration(info?.uptimeSeconds) },
-                { label: '启动时间', value: info?.startedAt ?? '-' },
-                { label: '数据库路径', value: info?.databasePath ?? '-' },
-              ]}
-            />
+            <Descriptions column={1} border data={[
+              { label: '版本', value: <Space>{info?.version ?? '-'}<Button size="mini" type="text" loading={checking} onClick={handleCheckUpdate}>检查更新</Button></Space> },
+              { label: '运行模式', value: info?.mode === 'release' ? <Tag color="green">生产</Tag> : <Tag color="orange">{info?.mode ?? '-'}</Tag> },
+              { label: '运行时长', value: formatDuration(info?.uptimeSeconds) },
+              { label: '启动时间', value: info?.startedAt ?? '-' },
+              { label: '数据库路径', value: <Typography.Text copyable>{info?.databasePath ?? '-'}</Typography.Text> },
+            ]} />
           </Card>
         </Col>
         <Col span={12}>
-          <Card title="部署资产">
-            <Space direction="vertical" size="medium" style={{ width: '100%' }}>
-              <Typography.Text>`deploy/nginx.conf`：静态资源托管与 `/api` 反向代理示例。</Typography.Text>
-              <Typography.Text>`deploy/backupx.service`：systemd 服务单元，负责守护 API 进程。</Typography.Text>
-              <Typography.Text>`deploy/install.sh`：一键安装示例脚本，用于创建目录、复制文件并启动服务。</Typography.Text>
-              <Typography.Text>`README.md`：包含完整部署与使用文档。</Typography.Text>
-            </Space>
+          <Card loading={loading} title="磁盘状态">
+            <Descriptions column={1} border data={[
+              { label: '总空间', value: formatBytes(info?.diskTotal) },
+              { label: '已用空间', value: formatBytes(info?.diskUsed) },
+              { label: '可用空间', value: formatBytes(info?.diskFree) },
+              { label: '使用率', value: info?.diskTotal ? `${((info.diskUsed / info.diskTotal) * 100).toFixed(1)}%` : '-' },
+            ]} />
           </Card>
         </Col>
       </Row>
 
-      <Card title="部署步骤">
-        <div className="code-block">{deploySteps.join('\n')}</div>
-      </Card>
+      {/* 更新检查结果 */}
+      {updateResult && (
+        <Card title="版本更新">
+          {updateResult.error ? (
+            <Typography.Text type="warning">{updateResult.error}</Typography.Text>
+          ) : updateResult.hasUpdate ? (
+            <Space direction="vertical" size="medium" style={{ width: '100%' }}>
+              <Space>
+                <Badge status="processing" />
+                <Typography.Text style={{ fontWeight: 600 }}>
+                  有新版本可用：{updateResult.latestVersion}
+                </Typography.Text>
+                <Typography.Text type="secondary">（当前：{updateResult.currentVersion}）</Typography.Text>
+              </Space>
+              {updateResult.publishedAt && (
+                <Typography.Text type="secondary">发布时间：{new Date(updateResult.publishedAt).toLocaleString()}</Typography.Text>
+              )}
+              {updateResult.releaseNotes && (
+                <Card size="small" title="更新说明" style={{ maxHeight: 200, overflow: 'auto' }}>
+                  <Typography.Paragraph style={{ whiteSpace: 'pre-wrap', marginBottom: 0 }}>{updateResult.releaseNotes}</Typography.Paragraph>
+                </Card>
+              )}
+              <Space>
+                {updateResult.downloadUrl && (
+                  <Link href={updateResult.downloadUrl} target="_blank">
+                    <Button type="primary">下载二进制包</Button>
+                  </Link>
+                )}
+                {updateResult.releaseUrl && (
+                  <Link href={updateResult.releaseUrl} target="_blank">
+                    <Button type="outline">查看 Release 详情</Button>
+                  </Link>
+                )}
+              </Space>
+              {updateResult.dockerImage && (
+                <Card size="small" title="Docker 更新命令">
+                  <Typography.Paragraph copyable code style={{ marginBottom: 0 }}>
+                    {`docker pull ${updateResult.dockerImage}:${updateResult.latestVersion} && docker compose up -d`}
+                  </Typography.Paragraph>
+                </Card>
+              )}
+            </Space>
+          ) : (
+            <Space>
+              <Badge status="success" />
+              <Typography.Text>当前已是最新版本 ({updateResult.currentVersion})</Typography.Text>
+            </Space>
+          )}
+        </Card>
+      )}
     </Space>
   )
 }

web/src/services/system.ts

@@ -11,11 +11,28 @@ export interface SystemInfo {
   diskUsed: number
 }
 
+export interface UpdateCheckResult {
+  currentVersion: string
+  latestVersion: string
+  hasUpdate: boolean
+  releaseUrl?: string
+  releaseNotes?: string
+  publishedAt?: string
+  downloadUrl?: string
+  dockerImage?: string
+  error?: string
+}
+
 export async function fetchSystemInfo() {
   const response = await http.get<{ code: string; message: string; data: SystemInfo }>('/system/info')
   return response.data.data
 }
 
+export async function checkUpdate() {
+  const response = await http.get<{ code: string; message: string; data: UpdateCheckResult }>('/system/update-check')
+  return response.data.data
+}
+
 export async function fetchSettings() {
   const response = await http.get<{ code: string; message: string; data: Record<string, string> }>('/settings')
   return response.data.data