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。

backend/static/assets/user-plus-DKeca2Dx.js

@@ -0,0 +1 @@
+import{i as e}from"./index-Dmami9WE.js";const y=[["path",{d:"M16 21v-2a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v2",key:"1yyitq"}],["circle",{cx:"9",cy:"7",r:"4",key:"nufk8"}],["line",{x1:"19",x2:"19",y1:"8",y2:"14",key:"1bvyxn"}],["line",{x1:"22",x2:"16",y1:"11",y2:"11",key:"1shjgl"}]],s=e("user-plus",y);export{s as U};