feat: Agent采集uptime, 后端持久化kernel/uptime/diskIO, 前端磁盘BPS+IOPS展示

- Agent: system.go 添加 readUptime(), SystemStat 携带 Uptime
- Backend: Server 模型新增 Kernel 字段, ReceiveReport 持久化 kernel+uptime
- Backend: /agent/latest 返回 kernel/uptime/port_info/disk_io_info/disk_total
- Frontend: 磁盘监控改为 BPS+IOPS (4张卡片), 系统信息修复内核/运行时长/监听端口/磁盘容量
- 图表单位从 MB/s 改为 KB/s, 添加 formatBPS 工具函数

frontend/src/App.tsx

@@ -21,6 +21,7 @@ import { AppReleaseManager } from '@/components/deploy/AppRelease';
 import { ApprovalFlowManager } from '@/components/approval/ApprovalFlow';
 import { ScriptManager } from '@/components/automation/ScriptManager';
 import { SystemManager } from '@/components/system/SystemManager';
+import { CredentialManager } from '@/components/system/CredentialManager';
 import { PipelineManager } from '@/components/deploy/PipelineManager';
 import { ReleaseManager } from '@/components/deploy/ReleaseManager';
 import { CronJobManager } from '@/components/automation/CronJobManager';
@@ -30,6 +31,7 @@ import { AIAlertAnalyzer } from '@/components/aiops/AIAlertAnalyzer';
 import { AIPredictiveAnalytics } from '@/components/aiops/AIPredictiveAnalytics';
 import AlertCenter from '@/components/monitor/alert-center/AlertCenter';
 import TraceManager from '@/components/monitor/trace/TraceManager';
+import { HostMonitor } from '@/pages/HostMonitor';
 import HostMonitorDashboard from '@/components/monitor/dashboard/HostMonitorDashboard';
 import GrafanaDashboard from '@/components/monitor/dashboard/GrafanaDashboard';
 import { MonitorCenter } from '@/pages/MonitorCenter';
@@ -76,6 +78,7 @@ function App() {
             <Route path="datasources" element={<DatasourcePage />} />
             <Route path="trace" element={<TraceManager />} />
             <Route path="dashboards" element={<GrafanaDashboard />} />
+            <Route path="host-monitor" element={<HostMonitor />} />
             <Route path="alerts" element={<AlertManager />} />
             <Route path="alert-center" element={<AlertCenter />} />
             <Route path="logs" element={<AlertManager />} />
@@ -92,6 +95,7 @@ function App() {
             <Route path="roles" element={<SystemManager />} />
             <Route path="logs-audit" element={<SystemManager />} />
             <Route path="terminal-audit" element={<SystemManager />} />
+            <Route path="credentials" element={<CredentialManager />} />
             <Route path="settings" element={<SystemManager />} />
             <Route path="*" element={<Navigate to="/" replace />} />
           </Route>