Additional React fixes

Fixed another issue that could occur in React powered pages

What's New in v2.0.0

### 🐛 Bug Fixes
- Fixed keyboard shortcuts - Alt+Shift+M now works reliably across all browsers
- Fixed arrow key movement - Use arrow keys to move overlays precisely (1px or 10px with Shift)
- Fixed coordinate display - Now shows accurate document coordinates instead of viewport positions
- Fixed positioning on scrolled pages - Overlays now appear exactly where you click, even when the page is scrolled
- Fixed memory leaks - Removed duplicate event listeners that could slow down your browser

### ✨ Improvements
- Better React compatibility - Now works smoothly on React applications without errors
- Improved color persistence - Your chosen border color is now saved between sessions
- Better error handling - More graceful failures with helpful debug messages
- Improved guide lines - Guide lines now resize properly when the browser window changes
- Better layering - Fixed visual stacking order of overlays, guides, and the ruler

### 🔧 Technical
- Improved coordinate system for accurate measurements on scrolled pages
- Enhanced storage error handling for better reliability
- Cleaner state management architecture
- Better null-safety in color calculations

Initial v1.0.0 release with core measurement functionality:

Distance and dimension measurement overlay
Keyboard shortcuts for precise control
Visual guidelines for alignment
Overlay color selection
Cross-browser compatibility
Performance optimized implementation