feat: Zabbix 数据源管理 — 完整 CRUD + 双 Tab 数据源页面

后端:
- models/zabbix_datasource.go: Zabbix 数据源 model (15字段, 参照 Grafana)
- handlers/zabbix_datasource.go: CRUD + 测试连接 (调用 Zabbix API Auth)
- routes.go: /zabbix-datasources 路由组
- database.go: AutoMigrate

前端:
- api.ts: zabbixDatasourceApi
- ZabbixDatasourceManager.tsx: 表单 (URL/用户名/密码/Trends设置/DB直连)
- DatasourcePage.tsx: Prometheus + Zabbix 双 Tab 包装
- App.tsx: /datasources 路由更新

frontend/src/App.tsx

@@ -33,7 +33,7 @@ import TraceManager from '@/components/monitor/trace/TraceManager';
 import HostMonitorDashboard from '@/components/monitor/dashboard/HostMonitorDashboard';
 import { MonitorCenter } from '@/pages/MonitorCenter';
 import { MetricsExplorer } from '@/pages/MetricsExplorer';
-import PrometheusDatasourceManager from '@/components/monitor/datasource/PrometheusDatasourceManager';
+import DatasourcePage from '@/components/monitor/datasource/DatasourcePage';
 
 const queryClient = new QueryClient({
   defaultOptions: {
@@ -75,7 +75,7 @@ function App() {
             <Route path="alert-center" element={<AlertCenter />} />
             <Route path="trace" element={<TraceManager />} />
             <Route path="dashboards" element={<HostMonitorDashboard />} />
-            <Route path="datasources" element={<PrometheusDatasourceManager />} />
+            <Route path="datasources" element={<DatasourcePage />} />
             <Route path="alerts" element={<AlertManager />} />
             <Route path="logs" element={<AlertManager />} />
             <Route path="approval" element={<ApprovalFlowManager />} />