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/app-navigation/AppDesktopShell.tsx

@@ -0,0 +1,239 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import {
+  View,
+  StyleSheet,
+  ScrollView,
+  TouchableOpacity,
+  Text,
+  Platform,
+} from 'react-native';
+import { useSafeAreaInsets, SafeAreaView } from 'react-native-safe-area-context';
+import { MaterialCommunityIcons } from '@expo/vector-icons';
+import { usePathname, useRouter } from 'expo-router';
+
+import { colors, shadows } from '../theme';
+import { useTotalUnreadCount } from '../stores';
+import { AppRouteStack } from './AppRouteStack';
+
+type TabName = 'HomeTab' | 'MessageTab' | 'ScheduleTab' | 'ProfileTab';
+
+const SIDEBAR_WIDTH_DESKTOP = 240;
+const SIDEBAR_WIDTH_TABLET = 200;
+const SIDEBAR_COLLAPSED_WIDTH = 72;
+
+const NAV_ITEMS: { name: TabName; label: string; href: string; icon: string; iconOutline: string }[] = [
+  { name: 'HomeTab', label: '首页', href: '/home', icon: 'home', iconOutline: 'home-outline' },
+  { name: 'MessageTab', label: '消息', href: '/messages', icon: 'message-text', iconOutline: 'message-text-outline' },
+  { name: 'ScheduleTab', label: '课表', href: '/schedule', icon: 'calendar-today', iconOutline: 'calendar-today' },
+  { name: 'ProfileTab', label: '我的', href: '/profile', icon: 'account', iconOutline: 'account-outline' },
+];
+
+function pathToTab(pathname: string): TabName {
+  if (pathname.startsWith('/messages')) return 'MessageTab';
+  if (pathname.startsWith('/schedule')) return 'ScheduleTab';
+  if (pathname.startsWith('/profile')) return 'ProfileTab';
+  if (pathname.startsWith('/home')) return 'HomeTab';
+  return 'HomeTab';
+}
+
+export function AppDesktopShell() {
+  const insets = useSafeAreaInsets();
+  const router = useRouter();
+  const pathname = usePathname();
+  const unreadCount = useTotalUnreadCount();
+  const [isCollapsed, setIsCollapsed] = useState(false);
+  const [isDesktop, setIsDesktop] = useState(false);
+
+  useEffect(() => {
+    if (Platform.OS !== 'web') return;
+    const check = () => {
+      const w = window.innerWidth || document.documentElement.clientWidth;
+      setIsDesktop(w >= SIDEBAR_WIDTH_DESKTOP);
+    };
+    check();
+    window.addEventListener('resize', check);
+    return () => window.removeEventListener('resize', check);
+  }, []);
+
+  const sidebarWidth = isCollapsed
+    ? SIDEBAR_COLLAPSED_WIDTH
+    : isDesktop
+      ? SIDEBAR_WIDTH_DESKTOP
+      : SIDEBAR_WIDTH_TABLET;
+
+  const currentTab = pathToTab(pathname || '/home');
+
+  const handleTabChange = useCallback(
+    (href: string) => {
+      router.replace(href);
+    },
+    [router]
+  );
+
+  return (
+    <View style={styles.container}>
+      <SafeAreaView
+        style={[
+          styles.sidebar,
+          { width: sidebarWidth, paddingTop: insets.top, paddingBottom: insets.bottom },
+        ]}
+      >
+        <View style={styles.sidebarHeader}>
+          <MaterialCommunityIcons name="carrot" size={32} color={colors.primary.main} />
+          {!isCollapsed && <Text style={styles.logoText}>胡萝卜BBS</Text>}
+        </View>
+        <ScrollView style={styles.sidebarContent} showsVerticalScrollIndicator={false}>
+          {NAV_ITEMS.map((item) => {
+            const isActive = currentTab === item.name;
+            const showBadge = item.name === 'MessageTab' && unreadCount > 0;
+            return (
+              <TouchableOpacity
+                key={item.name}
+                style={[
+                  styles.sidebarItem,
+                  isActive && styles.sidebarItemActive,
+                  isCollapsed && styles.sidebarItemCollapsed,
+                ]}
+                onPress={() => handleTabChange(item.href)}
+                activeOpacity={0.7}
+              >
+                <View style={styles.sidebarIconContainer}>
+                  <MaterialCommunityIcons
+                    name={(isActive ? item.icon : item.iconOutline) as any}
+                    size={24}
+                    color={isActive ? colors.primary.main : colors.text.secondary}
+                  />
+                  {showBadge ? (
+                    <View style={styles.badge}>
+                      <Text style={styles.badgeText}>{unreadCount > 99 ? '99+' : unreadCount}</Text>
+                    </View>
+                  ) : null}
+                </View>
+                {!isCollapsed ? (
+                  <Text style={[styles.sidebarLabel, isActive && styles.sidebarLabelActive]}>{item.label}</Text>
+                ) : null}
+              </TouchableOpacity>
+            );
+          })}
+        </ScrollView>
+        <TouchableOpacity
+          style={[styles.collapseButton, isCollapsed && styles.collapseButtonCollapsed]}
+          onPress={() => setIsCollapsed((c) => !c)}
+          activeOpacity={0.7}
+        >
+          <MaterialCommunityIcons
+            name={isCollapsed ? 'chevron-right' : 'chevron-left'}
+            size={24}
+            color={colors.text.secondary}
+          />
+        </TouchableOpacity>
+      </SafeAreaView>
+      <View style={styles.mainContent}>
+        <AppRouteStack />
+      </View>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    flexDirection: 'row',
+    backgroundColor: colors.background.default,
+  },
+  sidebar: {
+    backgroundColor: colors.background.paper,
+    borderRightWidth: 1,
+    borderRightColor: colors.divider,
+    flexDirection: 'column',
+    ...shadows.md,
+  },
+  sidebarHeader: {
+    paddingHorizontal: 16,
+    paddingVertical: 20,
+    borderBottomWidth: 1,
+    borderBottomColor: colors.divider,
+    alignItems: 'center',
+    justifyContent: 'center',
+    flexDirection: 'row',
+  },
+  logoText: {
+    fontSize: 18,
+    fontWeight: '700',
+    color: colors.primary.main,
+    marginLeft: 8,
+  },
+  sidebarContent: {
+    flex: 1,
+    paddingTop: 8,
+  },
+  sidebarItem: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    paddingHorizontal: 16,
+    paddingVertical: 12,
+    marginHorizontal: 8,
+    marginVertical: 4,
+    borderRadius: 12,
+  },
+  sidebarItemActive: {
+    backgroundColor: `${colors.primary.main}15`,
+  },
+  sidebarItemCollapsed: {
+    justifyContent: 'center',
+    paddingHorizontal: 0,
+  },
+  sidebarIconContainer: {
+    position: 'relative',
+    width: 40,
+    height: 40,
+    alignItems: 'center',
+    justifyContent: 'center',
+    borderRadius: 12,
+  },
+  sidebarLabel: {
+    fontSize: 15,
+    fontWeight: '500',
+    color: colors.text.secondary,
+    marginLeft: 12,
+    flex: 1,
+  },
+  sidebarLabelActive: {
+    color: colors.primary.main,
+    fontWeight: '600',
+  },
+  collapseButton: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    justifyContent: 'flex-end',
+    paddingHorizontal: 16,
+    paddingVertical: 12,
+    borderTopWidth: 1,
+    borderTopColor: colors.divider,
+  },
+  collapseButtonCollapsed: {
+    justifyContent: 'center',
+    paddingHorizontal: 0,
+  },
+  badge: {
+    position: 'absolute',
+    top: 2,
+    right: 2,
+    backgroundColor: colors.error.main,
+    borderRadius: 10,
+    minWidth: 18,
+    height: 18,
+    alignItems: 'center',
+    justifyContent: 'center',
+    paddingHorizontal: 4,
+  },
+  badgeText: {
+    color: colors.primary.contrast,
+    fontSize: 10,
+    fontWeight: '600',
+  },
+  mainContent: {
+    flex: 1,
+    backgroundColor: colors.background.default,
+  },
+});

src/app-navigation/AppRouteStack.tsx

@@ -0,0 +1,8 @@
+import { Stack } from 'expo-router';
+
+/**
+ * 已登录区内栈：由 app/(app) 下文件系统自动注册子路由
+ */
+export function AppRouteStack() {
+  return <Stack screenOptions={{ headerShown: false }} />;
+}