- 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.
- **Header:** Integrate `ThemeToggle` component into the user menu area.
- **Theme Provider:** Introduce `ThemeProvider` context for managing and persisting theme preferences.
- **New Components:** Add `ThemeToggle` for switching themes and `ThemeProvider` to handle state and system preferences.
- Ensure responsive updates and localStorage persistence for user-selected themes.
