## Cross-Platform PyInstaller Support
- Implemented persistent directory system for Windows (%APPDATA%), macOS (~/Library/Application Support), and Linux (/opt/MBetter)
- Added PyInstaller environment detection and automatic directory path optimization
- Created comprehensive directory utilities (app/utils/directories.py) with fallback mechanisms
- Enhanced configuration system to use persistent mbetterd.conf instead of .env for PyInstaller deployments

## Configuration System Enhancement
- Added configuration file migration system (migrate_config.py) for .env to mbetterd.conf transition
- Enhanced config.py with persistent config file loading and priority system (env vars > config file > defaults)
- Automatic config file discovery in persistent directories with fallback to local .env

## Authenticated ZIP Downloads
- Added new /api/download/zip/<match_id> endpoint with hybrid JWT/API token authentication
- Enhanced /api/updates endpoint to use authenticated download URLs instead of web routes
- Implemented access control ensuring users can only download their own match files (or admin access)
- Updated API routes to use persistent ZIP_UPLOADS_DIR for file serving

## Upload System Enhancement
- Modified file upload handlers to use persistent directories (ZIP_UPLOADS_DIR, FIXTURES_DIR, TEMP_DIR)
- Enhanced upload file paths to use appropriate persistent directories based on file type
- Updated main routes for ZIP downloads to use persistent directory paths
- Fixed PyInstaller temporary directory issues ensuring files persist between application restarts

## Documentation Updates
- Updated README.md with PyInstaller features, cross-platform compatibility, and authenticated downloads
- Enhanced CHANGELOG.md with comprehensive v1.2.1 release notes
- Added migration utility documentation and deployment instructions
- Updated version numbers and platform compatibility information

## Technical Improvements
- Enhanced error handling and logging throughout persistent directory operations
- Added comprehensive fallback mechanisms for various deployment scenarios
- Improved path handling with proper cross-platform directory structures
- Security enhancements for API file downloads with proper authentication validation