refactor(frontend): P1-P2 续 — API 子模块化、大组件拆分、Query 铺开

- api/server/ 与 api/cloud/ 子目录拆分，保持 @/api 导入不变
- hooks/api 新增 useCredentials、usePromDatasources，增强 useServers
- 拆分 CredentialManager、DeploymentWorkload、PrometheusDatasourceManager
- ServerManager、CredentialManager、PromDs 接入 TanStack Query

frontend/src/components/kubernetes/deployment-workload/ModalShell.tsx

@@ -0,0 +1,24 @@
+// ModalShell.tsx — 通用 Modal 外壳
+// 作者: Logan.Li
+import { Button } from '@/components/ui/button';
+import { X } from 'lucide-react';
+
+export interface ModalShellProps {
+  title: string;
+  children: React.ReactNode;
+  onClose: () => void;
+}
+
+export function ModalShell({ title, children, onClose }: ModalShellProps) {
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60" onClick={onClose}>
+      <div className="bg-slate-900 border border-slate-700 rounded-xl p-6 w-[460px] max-w-[90vw] shadow-2xl" onClick={e => e.stopPropagation()}>
+        <div className="flex items-center justify-between mb-4">
+          <h2 className="text-base font-bold text-slate-100">{title}</h2>
+          <Button variant="ghost" size="icon" className="h-7 w-7 text-slate-400" onClick={onClose}><X className="h-4 w-4" /></Button>
+        </div>
+        {children}
+      </div>
+    </div>
+  );
+}