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/src/app/providers.tsx

@@ -8,8 +8,7 @@ import { ThemeProvider } from '@/components/theme';
 // Set NEXT_PUBLIC_ENABLE_DEVTOOLS=true in .env.local to enable
 /* istanbul ignore next - Dev-only devtools, not tested in production */
 const ReactQueryDevtools =
-  process.env.NODE_ENV === 'development' &&
-  process.env.NEXT_PUBLIC_ENABLE_DEVTOOLS === 'true'
+  process.env.NODE_ENV === 'development' && process.env.NEXT_PUBLIC_ENABLE_DEVTOOLS === 'true'
     ? lazy(() =>
         import('@tanstack/react-query-devtools').then((mod) => ({
           default: mod.ReactQueryDevtools,