- Introduced `is_trakt_group` field in `PlaylistGroup` struct to differentiate between Trakt and non-Trakt groups.
- Updated relevant parsing functions in `m3u.rs`, `xtream.rs`, and `trakt.rs` to set this field appropriately.
- Enhanced sorting logic in `sort.rs` to prioritize Trakt groups during playlist sorting.
- Ensured backward compatibility by defaulting `is_trakt_group` to false where applicable.
euzu