refactor(api): Remove '/api' prefix from frontend API calls and config

- Removed '/api/' prefix from endpoint paths in auth.ts, notifications.ts, oauth.ts, and platform.ts to align with the backend URL reconfiguration.
- Updated 'API_BASE_URL' in config.ts to remove the '/api' suffix, ensuring that API requests are correctly routed to the root of the 'api' subdomain (e.g., http://api.lvh.me:8000/).
- Included improvements to login redirect logic in client.ts.

frontend/src/api/client.ts

@@ -88,11 +88,15 @@ apiClient.interceptors.response.use(
           return apiClient(originalRequest);
         }
       } catch (refreshError) {
-        // Refresh failed - clear tokens and redirect to login
+        // Refresh failed - clear tokens and redirect to login on root domain
         const { deleteCookie } = await import('../utils/cookies');
+        const { getBaseDomain } = await import('../utils/domain');
         deleteCookie('access_token');
         deleteCookie('refresh_token');
-        window.location.href = '/login';
+        const protocol = window.location.protocol;
+        const baseDomain = getBaseDomain();
+        const port = window.location.port ? `:${window.location.port}` : '';
+        window.location.href = `${protocol}//${baseDomain}${port}/login`;
         return Promise.reject(refreshError);
       }
     }