Release v1.2.0: Major performance and infrastructure improvements

Key highlights:
- 50x faster batch operations via get_videos_batch(), get_channels_batch()
- Unified authentication system (OAuth2 + API keys)
- Automatic retry logic with exponential backoff
- Smart caching for static data reduces quota usage
- Enhanced parameter validation prevents user errors
- New endpoints: live streams, YouTube Shorts, premieres
- Comprehensive helper functions for channel analysis
- Standardized error handling across all functions

This release significantly improves performance and reliability for production use cases while maintaining full backward compatibility.

remove cran release

add comment about yt_outh to all man pages