feat(frontend): i18n shared state components + UsersAdminPage + CHANGELOG

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/tests/Toast.test.tsx

@@ -28,7 +28,7 @@ describe('Toast', () => {
     expect(toast).toHaveTextContent('Session expirée');
     expect(toast).toHaveAttribute('data-kind', 'error');
 
-    await user.click(screen.getByRole('button', { name: /dismiss/i }));
+    await user.click(screen.getByRole('button', { name: /fermer/i }));
     await waitFor(() => {
       expect(screen.queryByTestId('toast')).toBeNull();
     });