Refactor useAuth hook, settings components, and docs for formatting and readability improvements

- Consolidated multi-line arguments into single lines where appropriate in `useAuth`.
- Improved spacing and readability in data processing across components (`ProfileSettingsForm`, `PasswordChangeForm`, `SessionCard`).
- Applied consistent table and markdown formatting in design system docs (e.g., `README.md`, `08-ai-guidelines.md`, `00-quick-start.md`).
- Updated code snippets to ensure adherence to Prettier rules and streamlined JSX structures.

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

@@ -16,9 +16,7 @@ describe('PreferencesPage', () => {
   it('renders placeholder message', () => {
     render(<PreferencesPage />);
 
-    expect(
-      screen.getByText(/Configure your preferences/)
-    ).toBeInTheDocument();
+    expect(screen.getByText(/Configure your preferences/)).toBeInTheDocument();
   });
 
   it('mentions Task 3.5', () => {