Update tests and e2e files to support locale-based routing

- Replaced static paths with dynamic locale subpaths (`/[locale]/*`) in imports, URLs, and assertions across tests.
- Updated `next-intl` mocks for improved compatibility with `locale`-aware components.
- Standardized `page.goto` and navigation tests with `/en` as the base locale for consistency.

frontend/tests/app/(authenticated)/settings/page.test.tsx

@@ -4,7 +4,7 @@
  */
 
 import { redirect } from 'next/navigation';
-import SettingsPage from '@/app/(authenticated)/settings/page';
+import SettingsPage from '@/app/[locale]/(authenticated)/settings/page';
 
 // Mock Next.js navigation - redirect throws to interrupt execution
 jest.mock('next/navigation', () => ({
@@ -18,8 +18,9 @@ describe('SettingsPage', () => {
     jest.clearAllMocks();
   });
 
-  it('redirects to /settings/profile', () => {
-    expect(() => SettingsPage()).toThrow('NEXT_REDIRECT');
-    expect(redirect).toHaveBeenCalledWith('/settings/profile');
+  it('redirects to /settings/profile with locale prefix', async () => {
+    const params = Promise.resolve({ locale: 'en' });
+    await expect(SettingsPage({ params })).rejects.toThrow('NEXT_REDIRECT');
+    expect(redirect).toHaveBeenCalledWith('/en/settings/profile');
   });
 });