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/services/api.ts

@@ -695,6 +695,17 @@ export const promDatasourceApi = {
   testConnection: (data: any) => http.post('/prometheus-datasources/test', data),
 };
 
+// ==================== Zabbix 数据源管理 API ==================== // Logan.Li
+export const zabbixDatasourceApi = {
+  list: () => http.get('/zabbix-datasources'),
+  get: (id: number | string) => http.get(`/zabbix-datasources/${id}`),
+  create: (data: any) => http.post('/zabbix-datasources', data),
+  update: (id: number | string, data: any) => http.put(`/zabbix-datasources/${id}`, data),
+  delete: (id: number | string) => http.delete(`/zabbix-datasources/${id}`),
+  setDefault: (id: number | string) => http.post(`/zabbix-datasources/${id}/default`),
+  testConnection: (data: any) => http.post('/zabbix-datasources/test', data),
+};
+
 // AI 智能助手 API（后端 LLM 配置 + 对话代理，OpenAI 兼容） // Logan.Li
 export interface LLMConfigData {
   configured?: boolean;