- Add ThemeProvider with system/light/dark mode support and localStorage persistence
- Add ThemeToggle component for pages without sidebar (landing, login, signup)
- Enable class-based dark mode in Tailwind CSS v4 via @custom-variant
- Add dark mode classes to landing page, login, signup, and all dashboard pages
- Keep IMPHNEN logo blue in dark mode, invert Kolosal logo
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
