SECURITY IMPROVEMENTS:
- Replaced all unsafe DOM manipulation with secure DOM API methods (createElement, appendChild, textContent)
- Enhanced XSS protection throughout popup and options pages
- Fixed 28 Firefox validation warnings for unsafe HTML assignment

FIREFOX STORE COMPLIANCE:
- Fixed add-on ID to match Firefox Add-ons store registration
- Removed unused permissions from manifest
- Improved build process for Firefox-specific requirements

CODE QUALITY:
- Added reusable helper functions for safe DOM manipulation
- Improved code maintainability and security best practices

All functionality remains unchanged - this is a security and compliance update. The extension now passes Firefox Add-ons store validation with zero security warnings.