- Consolidated and modularized `eslint.config.mjs` with defined rules for source, test, E2E, and scripts.
- Improved test and E2E rules with relaxed settings for flexibility and enhanced mocking.
- Standardized variable naming and removed redundant imports in unit and E2E tests.
- Updated error handling and comments to align with modern TypeScript best practices (e.g., `@ts-expect-error`).
- **ThemeToggle:** Introduce comprehensive tests to validate button functionality, dropdown options, and active theme indicators.
- **ThemeProvider:** Add tests for theme management, localStorage persistence, system preferences, and DOM updates.
- **Header & Footer:** Verify header rendering, user menu functionality, and footer content consistency.
- **AuthInitializer:** Ensure authentication state is correctly loaded from storage on mount.
