refactor(frontend): API 子模块化、大组件拆分与 TanStack Query hooks

P1: kubernetes/system API 拆为子目录模块，导出工具下沉到 lib/export-utils，
    http 统一 buildApiUrl/getWsBase；HostMonitor、DeploymentEdit* 拆至子组件。

P2: 新增 hooks/api（queryKeys、useTerminalSessions、useHostMonitor），
    TerminalSessionsTab 与 HostMonitor 接入 TanStack Query。

P3: 保留 services/api 路径，未迁移至 api/ 目录。

frontend/src/hooks/api/useTerminalSessions.ts

@@ -0,0 +1,70 @@
+// 终端会话列表 — TanStack Query // Logan.Li
+
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { terminalSessionApi } from '@/services/api';
+import { queryKeys } from './queryKeys';
+
+export interface TerminalSession {
+  id: number;
+  user_id?: number;
+  username: string;
+  server_id: number;
+  server_name: string;
+  server_ip: string;
+  server_port: number;
+  client_ip: string;
+  status: string;
+  duration: number;
+  record_size: number;
+  start_time: string;
+  end_time?: string | null;
+}
+
+type ListParams = {
+  page?: number;
+  page_size?: number;
+  server_id?: number;
+  username?: string;
+  status?: string;
+};
+
+function unwrapList<T>(data: unknown): T[] {
+  if (Array.isArray(data)) return data;
+  if (data && typeof data === 'object' && 'list' in data) {
+    return (data as { list: T[] }).list ?? [];
+  }
+  return [];
+}
+
+export function useTerminalSessions(params: ListParams = { page: 1, page_size: 100 }) {
+  return useQuery({
+    queryKey: queryKeys.terminalSessions(params),
+    queryFn: async () => {
+      const resp = await terminalSessionApi.list(params);
+      return unwrapList<TerminalSession>(resp);
+    },
+  });
+}
+
+export function useTerminalSessionMutations() {
+  const qc = useQueryClient();
+
+  const invalidate = () => qc.invalidateQueries({ queryKey: ['terminal-sessions'] });
+
+  const killMutation = useMutation({
+    mutationFn: (id: number) => terminalSessionApi.kill(id),
+    onSuccess: invalidate,
+  });
+
+  const deleteMutation = useMutation({
+    mutationFn: (id: number) => terminalSessionApi.delete(id),
+    onSuccess: invalidate,
+  });
+
+  const batchDeleteMutation = useMutation({
+    mutationFn: (ids: number[]) => terminalSessionApi.batchDelete(ids),
+    onSuccess: invalidate,
+  });
+
+  return { killMutation, deleteMutation, batchDeleteMutation, invalidate };
+}