iTunes appends featured-artist credits to track titles ('The Chase (feat. Y)') while the user's
file is often just 'The Chase'. _normalize_title only stripped the parens, keeping 'feat y' as
words, so the title-match ratio fell below the 0.6 substring floor — and with no track-number
rescue the track was reported 'no matching track in the iTunes tracklist' even though it was the
right song.
Strip feat/ft/featuring credits (parenthesised anywhere, or a bare trailing 'feat. X') before
normalizing, so both sides reduce to the same title and match exactly. Guarded so 'The Feat',
'Defeat', 'Lift' aren't touched, and version differentiators (Remix) still hard-reject.
Tests: 8 new (strip variants + the exact no-tn failure + cross-match/remix regressions); 63
existing reorganize tests still green.
