Major improvements:
- Add professional app icon with keyboard theme highlighting ESC/Shift keys
- Implement English input method selection (ABC, Unicode Hex Input, etc.)
- Add separate CJKV input method selection for better organization
- Fix alt+key shortcuts conflict by allowing non-ABC English input methods

Features added:
- New menu option "选择英文输入法" for English input method selection
- Enhanced InputMethodManager with separate English/CJKV method discovery
- Updated UserPreferences to store selected English input method
- Improved StatusBarManager with organized menu structure

UI/UX improvements:
- Updated usage instructions with new functionality description
- Better menu organization separating English and CJKV input method selection
- Professional app icon (AppIcon.icns) integrated into build process

Technical improvements:
- Refactored KeyboardManager to use configurable English input source
- Enhanced build script to automatically include app icons
- Added comprehensive CLAUDE.md for future development guidance
- Modernized GitHub Actions workflow resolving all CI issues
- Version bump to 0.7.0

This resolves issues with alt+key shortcuts when using ABC input method
and provides users full control over their preferred English input method.