feat(web): 主题设置联动 — 扩展 ThemeConfig 品牌字段 + 设置页面表单

- ThemeConfig 接口增加 brand_name/brand_slogan/brand_features/brand_copyright
- 新增 BrandConfig 接口和 getPublicBrand 公开品牌信息获取
- app store 增加 themeConfig 缓存和 loadThemeConfig 方法
- ThemeSettings 页面增加品牌设置表单（品牌名称/标语/特性/版权）

apps/web/src/stores/app.ts

@@ -1,4 +1,6 @@
 import { create } from 'zustand';
+import type { ThemeConfig } from '../api/themes';
+import { getTheme } from '../api/themes';
 
 export type ThemeName = 'blue' | 'warm' | 'dark' | 'emerald';
 
@@ -49,16 +51,25 @@ function loadTheme(): ThemeName {
 interface AppState {
   theme: ThemeName;
   sidebarCollapsed: boolean;
+  themeConfig: ThemeConfig | null;
   toggleSidebar: () => void;
   setTheme: (theme: ThemeName) => void;
+  loadThemeConfig: () => Promise<void>;
 }
 
 export const useAppStore = create<AppState>((set) => ({
   theme: loadTheme(),
   sidebarCollapsed: false,
+  themeConfig: null,
   toggleSidebar: () => set((s) => ({ sidebarCollapsed: !s.sidebarCollapsed })),
   setTheme: (theme) => {
     try { localStorage.setItem(STORAGE_KEY, theme); } catch {}
     set({ theme });
   },
+  loadThemeConfig: async () => {
+    try {
+      const config = await getTheme();
+      set({ themeConfig: config });
+    } catch {}
+  },
 }));