Features:
- Added comprehensive offline CDN fallback system with local Bootstrap and FontAwesome
- Enhanced cashier interface with streamlined navigation (logo + clock + user menu only)
- Implemented automatic CDN-to-local resource switching for network environments
- Added PyInstaller integration for offline functionality in executable builds

Technical Improvements:
- Fixed FontAwesome icon display issues with proper CDN priority and local fallback
- Optimized cashier navbar layout for focused, distraction-free interface
- Added local vendor directory with complete Bootstrap 5.3.0 and FontAwesome 6.0.0
- Implemented JavaScript-based resource availability detection
- Enhanced PyInstaller build configuration for automatic vendor file inclusion

Documentation Updates:
- Updated README.md with version 1.2.8 improvements
- Enhanced CHANGELOG.md with detailed feature descriptions
- Added comprehensive offline capabilities section to DOCUMENTATION.md
- Documented cashier interface navigation and access control

Files Modified:
- mbetterclient/web_dashboard/templates/base.html (CDN fallback, navbar layout)
- mbetterclient/web_dashboard/static/vendor/ (new directory with CDN resources)
- CHANGELOG.md, README.md, DOCUMENTATION.md (documentation updates)
- build.py (PyInstaller integration verified)

This release ensures MbetterClient works seamlessly in offline network environments while providing a cleaner, more focused cashier interface.