Covers API helpers (_get_similar_artists, _get_top_tags,
_get_similar_tracks, _search_track), config resolution, metadata
extraction from track titles, match score formatting, and both
commands (!similar, !tags) including play mode delegation, fallback
from track to artist similarity, and current-track integration.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
