Changes

PR #1681 by ksylvan: Enhance YouTube Support with Custom yt-dlp Arguments

• Add --yt-dlp-args flag for custom YouTube downloader options with advanced control capabilities
• Implement smart subtitle language fallback system when requested locale is unavailable
• Add fallback logic for YouTube subtitle language detection with auto-detection of downloaded languages
• Replace custom argument parser with shellquote and precompile regexes for improved performance and safety