Implement dark mode theme with system preference detection #48
Description
Description
Add dark mode support to the web application with system preference detection and manual toggle.
Expected Deliverables
- Create theme context/provider
- Add dark mode toggle in settings/header
- Support system preference (prefers-color-scheme)
- Persist user preference in localStorage
- Update Tailwind CSS configuration for dark mode
Requirements
- Smooth transitions between themes
- No flash of wrong theme on page load
- Support user preference override