refactor(frontend): P1-P2 架构统一 — utils/hooks/api 模块化

P1:
- utils/storage.ts、theme.ts、validate.ts + index 统一出口
- request/store/useTheme 接入 storage；清零 confirm/alert
- PipelineManager、TerminalAuditTab 拆分子模块（<700行红线）

P2:
- api/monitor、api/deploy 子目录化
- hooks/api 扩展：servers/pipelines/alerts/audit/sessionCommands
- PipelineManager、AuditOperationsTab 接入 TanStack Query

frontend/src/utils/theme.ts

@@ -0,0 +1,64 @@
+// 主题常量与持久化 — 供 useTheme / ThemeProvider 使用 // Logan.Li
+
+import { getItem, setItem, STORAGE_KEYS } from './storage';
+
+export type Theme =
+  | 'ocean-deep'
+  | 'light-professional'
+  | 'midnight-purple'
+  | 'pine-green'
+  | 'orange-vitality';
+
+export interface ThemeOption {
+  id: Theme;
+  name: string;
+  description: string;
+  isDark: boolean;
+  primaryColor: string;
+}
+
+export const THEME_OPTIONS: ThemeOption[] = [
+  { id: 'ocean-deep', name: '深海蓝', description: '专业稳重的深蓝色调', isDark: true, primaryColor: '#3b82f6' },
+  { id: 'light-professional', name: '明亮白', description: '清爽干净的浅色主题', isDark: false, primaryColor: '#2563eb' },
+  { id: 'midnight-purple', name: '午夜紫', description: '神秘优雅的紫色调', isDark: true, primaryColor: '#a855f7' },
+  { id: 'pine-green', name: '松林绿', description: '自然清新的绿色主题', isDark: true, primaryColor: '#22c55e' },
+  { id: 'orange-vitality', name: '活力橙', description: '温暖活力的橙色主题', isDark: true, primaryColor: '#f97316' },
+];
+
+export const THEME_ORDER: Theme[] = THEME_OPTIONS.map((o) => o.id);
+export const DEFAULT_THEME: Theme = 'ocean-deep';
+
+/** 兼容旧版 dark/light 主题名 // Logan.Li */
+export function migrateLegacyTheme(value: string | null): Theme | null {
+  if (value === 'dark') return 'ocean-deep';
+  if (value === 'light') return 'light-professional';
+  return null;
+}
+
+export function getInitialTheme(): Theme {
+  if (typeof window === 'undefined') return DEFAULT_THEME;
+  const stored = getItem(STORAGE_KEYS.theme);
+  const migrated = migrateLegacyTheme(stored);
+  if (migrated) {
+    setItem(STORAGE_KEYS.theme, migrated);
+    return migrated;
+  }
+  if (stored && THEME_ORDER.includes(stored as Theme)) {
+    return stored as Theme;
+  }
+  return DEFAULT_THEME;
+}
+
+export function persistTheme(theme: Theme): void {
+  setItem(STORAGE_KEYS.theme, theme);
+}
+
+export function applyThemeToDocument(theme: Theme): void {
+  if (typeof document === 'undefined') return;
+  document.documentElement.setAttribute('data-theme', theme);
+}
+
+export function getNextTheme(current: Theme): Theme {
+  const idx = THEME_ORDER.indexOf(current);
+  return THEME_ORDER[(idx + 1) % THEME_ORDER.length];
+}