Link "Now Playing" track to original YouTube video

[paulpv]

Summary

When a track sourced from YouTube is playing, the "Now Playing" song title in the UI should link to the original YouTube video so users can easily jump to the source.

Motivation

• Provides quick attribution and context for the current track.
• Enables users to share or re-open the original video without searching manually.
• Aligns with user expectations from other media players that link back to source content.

Acceptance Criteria

• If the current track comes from YouTube, the "Now Playing" song title renders as a hyperlink to the original video URL.
• Opening the link should respect the user's default browser behavior (new tab/window).
• Tracks without an associated YouTube URL continue to render as plain text.

Additional Notes

• Consider how the URL will be stored or passed alongside the track metadata so the link remains available.
• Ensure the design remains accessible and that the link state is communicated clearly (e.g., hover/focus styles).

[paulpv]

Heads-up on existing behaviour: the history list already derives a YouTube URL from each entry when possible. In player.html the helper resolveYouTubeUrl (around line 1470) inspects the track name and relative path, strips the file extension, and looks for a trailing [VIDEO_ID] token. When it finds a match, it turns that into https://youtu.be/<id> and uses it while rendering the history rows. That is why history entries with filenames like My Track [abcd1234].m4a already expose a clickable link to the original video. The feature request here would simply bring the same extraction to the "Now Playing" header.