- library.rs: scans channels/<name>/ into channels + videos by filename stem
- downloader.rs: runs yt-dlp in a background thread, streams progress to the UI
- app.rs / main.rs: channel sidebar, searchable thumbnail list, detail/description
panel, downloads panel; plays videos via mpv (falls back to xdg-open)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>