Add refresh token functionality and improve login response handling

- Introduced RefreshTokenView to allow users to refresh their access tokens using a valid refresh token.
- Enhanced LoginView to ensure correct user/account loading and improved error handling during user serialization.
- Updated API response structure to include access and refresh token expiration times.
- Adjusted frontend API handling to support both new and legacy token response formats.

frontend/src/services/api.ts

@@ -194,13 +194,14 @@ export async function fetchAPI(endpoint: string, options?: RequestInit & { timeo
 
           if (refreshResponse.ok) {
             const refreshData = await refreshResponse.json();
-            if (refreshData.success && refreshData.access) {
+            const accessToken = refreshData.data?.access || refreshData.access;
+            if (refreshData.success && accessToken) {
               // Update token in store
               try {
                 const authStorage = localStorage.getItem('auth-storage');
                 if (authStorage) {
                   const parsed = JSON.parse(authStorage);
-                  parsed.state.token = refreshData.access;
+                  parsed.state.token = accessToken;
                   localStorage.setItem('auth-storage', JSON.stringify(parsed));
                 }
               } catch (e) {
@@ -210,7 +211,7 @@ export async function fetchAPI(endpoint: string, options?: RequestInit & { timeo
               // Retry original request with new token
               const newHeaders = {
                 ...headers,
-                'Authorization': `Bearer ${refreshData.access}`,
+                'Authorization': `Bearer ${accessToken}`,
               };
               
               const retryResponse = await fetch(`${API_BASE_URL}${endpoint}`, {