feat(ui): 浅蓝主题、外观设置与圆桌看板主题适配，优化工作区布局

新增 lightblue 主题与外观设置联动，圆桌 Step3 看板/report 统一配色；工作区侧边栏、输入框与轻应用 iframe 主题参数同步更新。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/src/contexts/ThemeContext.tsx

@@ -10,7 +10,7 @@ import { useTheme as useNextTheme } from 'next-themes';
 import { useAppearanceSettings } from '@/core/system-settings/hooks';
 
 // 主题类型
-export type ThemeType = 'dark' | 'light';
+export type ThemeType = 'dark' | 'light' | 'lightblue';
 
 // 主题配置
 export interface ThemeConfig {
@@ -82,6 +82,28 @@ const themes: Record<ThemeType, ThemeConfig> = {
       overlay: 'black/30',
     },
   },
+  lightblue: {
+    type: 'lightblue',
+    name: '浅蓝主题',
+    colors: {
+      background: 'white',
+      backgroundSecondary: 'blue-50',
+      text: 'gray-800',
+      textSecondary: 'gray-500',
+      primary: 'blue-600',
+      primaryHover: 'blue-500',
+      border: 'blue-200',
+      accent: 'blue-700',
+      success: 'emerald-600',
+      warning: 'amber-500',
+      error: 'red-600',
+      card: 'white',
+      cardHover: 'blue-50',
+      input: 'white',
+      inputBorder: 'blue-200',
+      overlay: 'black/30',
+    },
+  },
 };
 
 const STORAGE_KEY = 'strategy-theme';
@@ -97,7 +119,9 @@ function readPersistedTheme(): ThemeType {
     return 'light';
   }
   const saved = localStorage.getItem(STORAGE_KEY);
-  return saved === 'dark' ? 'dark' : 'light';
+  if (saved === 'dark') return 'dark';
+  if (saved === 'lightblue') return 'lightblue';
+  return 'light';
 }
 
 function hasExplicitChoice(): boolean {
@@ -151,7 +175,12 @@ export const ThemeProvider: React.FC<ThemeProviderProps> = ({ children }) => {
     const current = localStorage.getItem(STORAGE_KEY);
     const legacy = localStorage.getItem('theme');
 
-    if (current && current !== 'light' && current !== 'dark') {
+    if (
+      current &&
+      current !== 'light' &&
+      current !== 'dark' &&
+      current !== 'lightblue'
+    ) {
       // Garbage value — wipe it so the boot-sync below can take over.
       localStorage.removeItem(STORAGE_KEY);
     }
@@ -185,7 +214,9 @@ export const ThemeProvider: React.FC<ThemeProviderProps> = ({ children }) => {
   const theme: ThemeType = mounted
     ? effectiveTheme === 'dark'
       ? 'dark'
-      : 'light'
+      : effectiveTheme === 'lightblue'
+        ? 'lightblue'
+        : 'light'
     : readPersistedTheme();
 
   useEffect(() => {