refactor(App, navigation): migrate to Expo Router and clean up navigation structure

- Updated App entry point to utilize Expo Router, simplifying the navigation setup.
- Removed legacy navigation components and services to streamline the codebase.
- Adjusted package.json to reflect the new entry point and updated dependencies for compatibility.
- Enhanced overall application structure by consolidating navigation logic and improving maintainability.

src/screens/message/NotificationsScreen.tsx

@@ -18,17 +18,16 @@ import {
 } from 'react-native';
 import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context';
 import { useIsFocused } from '@react-navigation/native';
-import { useNavigation } from '@react-navigation/native';
-import { NativeStackNavigationProp } from '@react-navigation/native-stack';
+import { useRouter } from 'expo-router';
 import { MaterialCommunityIcons } from '@expo/vector-icons';
 import { colors, spacing, borderRadius, shadows } from '../../theme';
 import { SystemMessageResponse } from '../../types/dto';
 import { messageService } from '../../services/messageService';
 import { commentService } from '../../services/commentService';
 import { SystemMessageItem } from '../../components/business';
-import { Text, EmptyState, ResponsiveContainer } from '../../components/common';
+import { Text, EmptyState, ResponsiveContainer, AppBackButton } from '../../components/common';
 import { useCursorPagination } from '../../hooks/useCursorPagination';
-import { RootStackParamList } from '../../navigation/types';
+import * as hrefs from '../../navigation/hrefs';
 import { useMessageManagerSystemUnreadCount } from '../../stores';
 import { messageManager } from '../../stores/messageManager';
 
@@ -48,7 +47,7 @@ const GROUP_SYSTEM_TYPES = new Set(['group_invite', 'group_join_apply', 'group_j
 export const NotificationsScreen: React.FC<{ onBack?: () => void }> = ({ onBack }) => {
   const isFocused = useIsFocused();
   const { setSystemUnreadCount, decrementSystemUnreadCount } = useMessageManagerSystemUnreadCount();
-  const navigation = useNavigation<NativeStackNavigationProp<RootStackParamList>>();
+  const router = useRouter();
 
   // 修复竞态条件：使用本地状态管理窗口尺寸，避免 hydration 问题
   const [windowSize, setWindowSize] = useState({ width: 0, height: 0 });
@@ -291,17 +290,17 @@ export const NotificationsScreen: React.FC<{ onBack?: () => void }> = ({ onBack
       ) {
         const postId = await resolvePostId(message);
         if (postId) {
-          navigation.navigate('PostDetail', { postId });
+          router.push(hrefs.hrefPostDetail(postId));
         }
       } else if (system_type === 'follow') {
         // 关注 - 跳转到用户主页
         if (extra_data?.actor_id_str) {
-          navigation.navigate('UserProfile', { userId: extra_data.actor_id_str });
+          router.push(hrefs.hrefUserProfile(extra_data.actor_id_str));
         }
       } else if (system_type === 'group_join_apply') {
-        navigation.navigate('GroupRequestDetail', { message });
+        router.push(hrefs.hrefGroupRequestDetail(message));
       } else if (system_type === 'group_invite') {
-        navigation.navigate('GroupInviteDetail', { message });
+        router.push(hrefs.hrefGroupInviteDetail(message));
       }
       // 其他类型暂不处理跳转
     } catch (error) {
@@ -316,7 +315,7 @@ export const NotificationsScreen: React.FC<{ onBack?: () => void }> = ({ onBack
     const actorId = extra_data?.actor_id_str || (extra_data?.actor_id ? String(extra_data.actor_id) : null);
     
     if (actorId) {
-      navigation.navigate('UserProfile', { userId: actorId });
+      router.push(hrefs.hrefUserProfile(actorId));
     }
   };
 
@@ -350,13 +349,7 @@ export const NotificationsScreen: React.FC<{ onBack?: () => void }> = ({ onBack
     return (
       <View style={[styles.header, isWideScreen ? styles.headerWide : null]}>
         {shouldShowBackButton ? (
-          <TouchableOpacity
-            style={styles.backButton}
-            onPress={onBack}
-            activeOpacity={0.7}
-          >
-            <MaterialCommunityIcons name="arrow-left" size={24} color={colors.text.primary} />
-          </TouchableOpacity>
+          <AppBackButton style={styles.backButton} onPress={onBack} />
         ) : (
           <View style={styles.backButtonPlaceholder} />
         )}