- 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.
- Replaced `useAuthStore` imports with `useAuth` from `AuthContext` in `AuthGuard` and `Header` for consistency.
- Enhanced `getAuthStore` to prioritize E2E test store injection for improved testability.
- Updated comments to reflect changes and clarify usage patterns.
- Consolidated `useAuthStore` into the unified `useAuth` hook for cleaner imports and consistency across frontend components.
- Enhanced database management in Alembic migrations by introducing `ensure_database_exists` to automatically create the database if missing.
- Refactor `text-*` and `bg-*` classes to use semantic color tokens such as `foreground`, `muted-foreground`, `card`, and `accent`.
- Adjust `Header`, `Footer`, and settings pages to align with the OKLCH-based design system.
- Ensure visual consistency and accessibility for both light and dark themes.
- **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.
