feat: 完善认证系统

- 修复 Storage 层使用 AsyncStorage
- 统一 Token 存储键名为 bestaibest.better-auth.session_token
- 启用 401 自动跳转登录页并显示 Toast 提示
- 添加全局认证守卫（AuthGuard 组件）
- 修复 x-ownerid header 配置（从环境变量读取商户ID）
- 导出 loomart API 供活动数据使用

主要修改:
- lib/storage.native.ts: 新建，使用 AsyncStorage
- lib/storage.ts: 添加错误处理和注释
- lib/fetch-logger.ts: 统一 Token 键，启用 401 拦截
- lib/auth.ts: 导出 TOKEN_KEY，修复 x-ownerid，导出 loomart
- app/_layout.tsx: 添加 AuthGuard 组件实现路由守卫

Co-Authored-By: Claude <noreply@anthropic.com>

app/_layout.tsx

@@ -1,43 +1,110 @@
 import '../global.css'
 
 import { DarkTheme, DefaultTheme, ThemeProvider } from '@react-navigation/native'
-import { Stack } from 'expo-router'
+import { Stack, usePathname, useRouter } from 'expo-router'
 import { StatusBar } from 'expo-status-bar'
+import { useEffect } from 'react'
 import 'react-native-reanimated'
 import { GestureHandlerRootView } from 'react-native-gesture-handler'
+import { View, ActivityIndicator } from 'react-native'
 
 import { useColorScheme } from '@/hooks/use-color-scheme'
 import { KeyboardProvider } from 'react-native-keyboard-controller'
 import { SafeAreaProvider } from 'react-native-safe-area-context'
 import { ModalPortal } from '@/components/ui'
 import '@/lib/i18n'
+import { useSession } from '@/lib/auth'
 
 export const unstable_settings = {
     anchor: '(tabs)',
 }
 
+// 受保护的路由（需要登录才能访问）
+const PROTECTED_ROUTES = [
+    '/(tabs)',
+    '/channels',
+    '/generateVideo',
+    '/generationRecord',
+    '/worksList',
+    '/membership',
+    '/changePassword',
+]
+
+// 公开路由（无需登录）
+const PUBLIC_ROUTES = [
+    '/auth',
+    '/modal',
+    '/searchTemplate',
+    '/searchResults',
+    '/searchWorks',
+    '/searchWorksResults',
+    '/templateDetail',
+    '/terms',
+    '/privacy',
+]
+
+// 认证守卫组件
+function AuthGuard({ children }: { children: React.ReactNode }) {
+    const pathname = usePathname()
+    const router = useRouter()
+    const { data: session, isPending } = useSession()
+
+    useEffect(() => {
+        // 加载中不处理
+        if (isPending) return
+
+        // 检查是否在受保护路由
+        const isProtectedRoute = PROTECTED_ROUTES.some(route => pathname?.startsWith(route))
+
+        // 未登录访问受保护路由 -> 跳转到登录页
+        if (isProtectedRoute && !session?.user) {
+            router.replace('/auth')
+            return
+        }
+
+        // 已登录访问登录页 -> 跳转到首页
+        if (pathname === '/auth' && session?.user) {
+            router.replace('/(tabs)')
+            return
+        }
+    }, [pathname, session, isPending, router])
+
+    // 加载中显示 loading
+    if (isPending) {
+        return (
+            <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center', backgroundColor: '#090A0B' }}>
+                <ActivityIndicator size="large" color="#9966FF" />
+            </View>
+        )
+    }
+
+    return <>{children}</>
+}
+
 // 路由层
 export default function RootLayout() {
     return (
         <Providers>
-            <Stack>
-                <Stack.Screen name="auth" options={{ headerShown: false }} />
-                <Stack.Screen name="modal" options={{ presentation: 'modal', title: 'Modal' }} />
-                <Stack.Screen name="(tabs)" options={{ headerShown: false }} />
-                <Stack.Screen name="channels" options={{ headerShown: false }} />
-                <Stack.Screen name="searchTemplate" options={{ headerShown: false }} />
-                <Stack.Screen name="searchResults" options={{ headerShown: false }} />
-                <Stack.Screen name="generationRecord" options={{ headerShown: false }} />
-                <Stack.Screen name="generateVideo" options={{ headerShown: false }} />
-                <Stack.Screen name="templateDetail" options={{ headerShown: false }} />
-                <Stack.Screen name="membership" options={{ headerShown: false }} />
-                <Stack.Screen name="terms" options={{ headerShown: false }} />
-                <Stack.Screen name="privacy" options={{ headerShown: false }} />
-                <Stack.Screen name="worksList" options={{ headerShown: false }} />
-                <Stack.Screen name="searchWorks" options={{ headerShown: false }} />
-                <Stack.Screen name="searchWorksResults" options={{ headerShown: false }} />
-                <Stack.Screen name="changePassword" options={{ headerShown: false }} />
-            </Stack>
+            <AuthGuard>
+                <Stack>
+                    <Stack.Screen name="auth" options={{ headerShown: false }} />
+                    <Stack.Screen name="modal" options={{ presentation: 'modal', title: 'Modal' }} />
+                    <Stack.Screen name="(tabs)" options={{ headerShown: false }} />
+                    <Stack.Screen name="channels" options={{ headerShown: false }} />
+                    <Stack.Screen name="searchTemplate" options={{ headerShown: false }} />
+                    <Stack.Screen name="searchResults" options={{ headerShown: false }} />
+                    <Stack.Screen name="generationRecord" options={{ headerShown: false }} />
+                    <Stack.Screen name="generateVideo" options={{ headerShown: false }} />
+                    <Stack.Screen name="templateDetail" options={{ headerShown: false }} />
+                    <Stack.Screen name="membership" options={{ headerShown: false }} />
+                    <Stack.Screen name="terms" options={{ headerShown: false }} />
+                    <Stack.Screen name="privacy" options={{ headerShown: false }} />
+                    <Stack.Screen name="worksList" options={{ headerShown: false }} />
+                    <Stack.Screen name="searchWorks" options={{ headerShown: false }} />
+                    <Stack.Screen name="searchWorksResults" options={{ headerShown: false }} />
+                    <Stack.Screen name="changePassword" options={{ headerShown: false }} />
+                </Stack>
+            </AuthGuard>
             <StatusBar style="auto" />
         </Providers>
     )