refactor(frontend): services/api 迁至 src/api，http 迁至 utils/request

对齐 Vue 后台惯例：
- src/api/          域 API（原 services/api）
- src/utils/request.ts  HTTP 封装（原 services/http.ts）
- src/utils/export.ts  客户端导出工具
- src/utils/index.ts   工具统一出口

全局导入改为 @/api 与 @/utils/request，tsc + build 通过。

frontend/src/api/kubernetes/namespace.ts

@@ -0,0 +1,14 @@
+// Kubernetes Namespace API // Logan.Li
+
+import { http } from '@/utils/request';
+
+export const namespaceApi = {
+  getNamespaces: async (clusterCode: string) => http.get(`/kubernetes/${clusterCode}/namespaces`),
+  getNamespacesDetail: async (clusterCode: string) => http.get(`/kubernetes/${clusterCode}/namespaces/detail`),
+  getNamespaceDetail: async (clusterCode: string, namespace: string) =>
+    http.get(`/kubernetes/${clusterCode}/namespace/${namespace}/detail`),
+  createNamespace: async (clusterCode: string, name: string, labels?: Record<string, string>) =>
+    http.post(`/kubernetes/${clusterCode}/namespaces`, { name, labels: labels || {} }),
+  deleteNamespace: async (clusterCode: string, namespace: string) =>
+    http.delete(`/kubernetes/${clusterCode}/namespaces/${namespace}`),
+};