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/hooks/api/index.ts

@@ -4,7 +4,9 @@ export { queryKeys } from './queryKeys';
 export { unwrapList, unwrapTotal } from './unwrap';
 export { useTerminalSessions, useTerminalSessionMutations, type TerminalSession } from './useTerminalSessions';
 export { useHostList, useHostHistory, useHealthProbes, usePortPolicy } from './useHostMonitor';
-export { useServers, useServerMutations } from './useServers';
+export { useServers, useServerMutations, type ServerRecord } from './useServers';
+export { useCredentials, useCredentialDetail, useCredentialMutations, type CredentialRecord } from './useCredentials';
+export { usePromDatasources, usePromDatasourceMutations, type PromDatasource } from './usePromDatasources';
 export { usePipelines, usePipelineRuns, usePipelineMutations } from './usePipelines';
 export { useAlertRules, useAlerts, useAlertMutations } from './useAlerts';
 export { useAuditLogs } from './useAuditLogs';