feat: add support for {composer} tag with smart path formatting

[edisun3003]

Pull Request Description: Add {composer} Tag Support

Title: feat: Add {composer} tag support with smart path formatting

Description

This PR adds support for a {composer} variable in the track path formatter and metadata embedding.

Why this is needed (The Tamil Music/Apple Music Problem)

When downloading soundtracks—specifically Tamil movie songs from Apple Music—the Album Artist tag is often inconsistent or missing, while the Composer field is almost always populated with the primary music director (e.g., A.R. Rahman, Anirudh).

Currently, users have to rely on {artist}, which can lead to fragmented folder structures if multiple artists are featured on a track. By adding {composer}, users can reliably organize their library by the actual music director.

Key Changes

1. Metadata Extraction: Added explicit extraction of composerName for Apple Music and writers for Spotify credits.
2. Smart Path Formatting: Added a logic refinement for the {composer} path variable. If the composer field contains multiple names (e.g., A.R. Rahman & Na. Muthukumar), the path formatter will only use the first name for the folder structure to keep libraries clean.
3. Full Metadata Preservation: While the folder path uses the primary name, the full list of names is still embedded into the file's internal metadata tags (mapping to TCOM for MP3/ID3).
4. Configuration: Added an embed_composer toggle in the settings.

Verification Results

• Tested with Apple Music URLs.
• Verified that Tracks/{composer}/{album}/ correctly creates folders using only the lead composer's name.
• Verified that ID3 tags correctly contain the full composer string via MP3Tag/ffprobe.

[moddroid94]

i'm not really sure how this could help given the state of the app, but it's a simple change, but we should add a toggle in the ui, it's not going to pick it up automatically i think.