The manual match modal for Genius only returned 0 or 1 artist result
because search_artist() searched songs (per_page=5), extracted the
primary artist, and returned the first match or None.
Added search_artists() that returns multiple unique artists extracted
from song results with broader search (per_page=20). The manual match
endpoint now shows up to 8 artist candidates and multiple track results
instead of one-or-nothing. Also shows the Genius URL as extra info.
