* Add complete Spanish translation (README.es.md)
* Restructure English README for clarity and conciseness
* Filter out YouTube Shorts from channel video listings (sort=4)
* Add fallback for video count using playlist metadata when API returns zero
* Add get_playlist_metadata() to fetch metadata without full video list
* Add is_short() utility to detect YouTube Shorts by duration, badges, and type
* Export is_short from yt_data_extract for use across modules
