Fix session persistence issue

- Created SSR-safe tokenStorage utility for localStorage access
- Updated AuthContext with window availability checks
- Enhanced API client interceptors with SSR safety
- Improved error handling to only clear tokens on auth errors (401/403)
- Added token refresh support for multiple response structures
- Added redirect loop prevention in auth flow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

maternal-web/lib/auth/AuthContext.tsx

@@ -3,6 +3,7 @@
 import { createContext, useContext, useEffect, useState, ReactNode } from 'react';
 import { useRouter } from 'next/navigation';
 import apiClient from '@/lib/api/client';
+import { tokenStorage } from '@/lib/utils/tokenStorage';
 
 export interface User {
   id: string;
@@ -45,23 +46,46 @@ export const AuthProvider = ({ children }: { children: ReactNode }) => {
 
   // Check authentication status on mount
   useEffect(() => {
-    checkAuth();
+    // Only run on client side
+    if (typeof window !== 'undefined') {
+      checkAuth();
+    } else {
+      setIsLoading(false);
+    }
   }, []);
 
   const checkAuth = async () => {
-    const token = localStorage.getItem('accessToken');
-    if (!token) {
+    // Ensure we're on client side
+    if (typeof window === 'undefined') {
       setIsLoading(false);
       return;
     }
 
     try {
+      const token = tokenStorage.getAccessToken();
+      if (!token) {
+        setIsLoading(false);
+        return;
+      }
+
       const response = await apiClient.get('/api/v1/auth/me');
-      setUser(response.data.data);
-    } catch (error) {
+
+      // Check if response has expected structure
+      if (response.data?.data) {
+        setUser(response.data.data);
+      } else if (response.data?.user) {
+        // Handle alternative response structure
+        setUser(response.data.user);
+      } else {
+        throw new Error('Invalid response structure');
+      }
+    } catch (error: any) {
       console.error('Auth check failed:', error);
-      localStorage.removeItem('accessToken');
-      localStorage.removeItem('refreshToken');
+      // Only clear tokens if it's an actual auth error (401, 403)
+      if (error?.response?.status === 401 || error?.response?.status === 403) {
+        tokenStorage.clearTokens();
+        setUser(null);
+      }
     } finally {
       setIsLoading(false);
     }
@@ -86,8 +110,7 @@ export const AuthProvider = ({ children }: { children: ReactNode }) => {
       const { data: responseData } = response.data;
       const { tokens, user: userData } = responseData;
 
-      localStorage.setItem('accessToken', tokens.accessToken);
-      localStorage.setItem('refreshToken', tokens.refreshToken);
+      tokenStorage.setTokens(tokens.accessToken, tokens.refreshToken);
       setUser(userData);
 
       router.push('/');
@@ -123,8 +146,7 @@ export const AuthProvider = ({ children }: { children: ReactNode }) => {
 
       const { accessToken, refreshToken } = tokens;
 
-      localStorage.setItem('accessToken', accessToken);
-      localStorage.setItem('refreshToken', refreshToken);
+      tokenStorage.setTokens(accessToken, refreshToken);
       setUser(userData);
 
       // Redirect to onboarding
@@ -141,8 +163,7 @@ export const AuthProvider = ({ children }: { children: ReactNode }) => {
     } catch (error) {
       console.error('Logout failed:', error);
     } finally {
-      localStorage.removeItem('accessToken');
-      localStorage.removeItem('refreshToken');
+      tokenStorage.clearTokens();
       setUser(null);
       router.push('/login');
     }