refactor(frontend): Remove '/api' prefix from all API calls to align with backend URL convention

- Updated all API endpoint strings in 'frontend/src' (via sed and manual fixes) to remove the '/api/' prefix.
- Manually fixed 'Timeline.tsx' absolute URLs to use the 'api' subdomain and correct path.
- Manually fixed 'useAuth.ts' logout fetch URLs.
- Updated 'HelpApiDocs.tsx' sandbox URL.
- This change, combined with the backend URL update, fully transitions the application to use subdomain-based routing (e.g., 'http://api.lvh.me:8000/resource/') instead of path-prefix routing (e.g., 'http://api.lvh.me:8000/api/resource/').

frontend/src/App.tsx

@@ -252,9 +252,10 @@ const AppContent: React.FC = () => {
     const isRootDomainForUnauthUser = currentHostname === baseDomain || currentHostname === 'localhost';
 
     if (!isRootDomainForUnauthUser) {
-      // Redirect to root domain login
+      // Redirect to root domain login (preserve port)
       const protocol = window.location.protocol;
-      window.location.href = `${protocol}//${baseDomain}/login`;
+      const port = window.location.port ? `:${window.location.port}` : '';
+      window.location.href = `${protocol}//${baseDomain}${port}/login`;
       return <LoadingScreen />;
     }