feat(message): add embedded mode to ChatScreen for desktop dual-column layout

Replace EmbeddedChat with unified ChatScreen supporting embedded mode through props. Pass conversation data, layout constraints, and navigation callbacks directly to ChatScreen instead of using separate embedded component. Consolidates dual-column layout logic into single component with conditional rendering based on isEmbedded prop.

src/screens/message/MessageListScreen.tsx

@@ -54,8 +54,8 @@ import {
 import { Avatar, Text, EmptyState, ResponsiveContainer, AppBackButton } from '../../components/common';
 import { useResponsive, useBreakpointGTE } from '../../hooks/useResponsive';
 import * as hrefs from '../../navigation/hrefs';
-// 导入 EmbeddedChat 组件用于桌面端双栏布局
-import { EmbeddedChat } from './components/EmbeddedChat';
+// 导入 ChatScreen 组件用于桌面端双栏布局
+import { ChatScreen } from './ChatScreen';
 import { ConversationListRow } from './components/ConversationListRow';
 // 导入 NotificationsScreen 用于在内部显示
 import { NotificationsScreen } from './NotificationsScreen';
@@ -852,9 +852,13 @@ export const MessageListScreen: React.FC = () => {
               <NotificationsScreen onBack={() => setShowNotifications(false)} />
             ) : selectedConversation ? (
               // 显示选中会话的聊天内容
-              <EmbeddedChat 
-                conversation={selectedConversation}
-                onBack={() => setSelectedConversation(null)}
+              <ChatScreen
+                isEmbedded
+                embeddedConversationId={String(selectedConversation.id)}
+                embeddedIsGroupChat={selectedConversation.type === 'group'}
+                embeddedGroupId={selectedConversation.group ? String(selectedConversation.group.id) : undefined}
+                embeddedGroupName={selectedConversation.group?.name}
+                onEmbeddedBack={() => setSelectedConversation(null)}
               />
             ) : (
               // 默认占位符