The ThemeToggle component was causing hydration errors because the server
and client rendered different icons (Sun/Moon) based on the theme state.
Changes:
- Render a placeholder button until component is mounted
- Only render the actual theme icon after client-side hydration
- This ensures server and client HTML match during initial render
Fixes console error: 'Expected server HTML to contain a matching <circle> in <svg>'
david_bai
e4ca70d758