When a track's duration is known but nothing matches the duration window, the
cascade no longer falls back to blind title-only/no-filter grabs (which pulled
same-titled videos by other uploaders, e.g. a "recognize" fan clip). Instead it
relaxes only the duration constraint while still REQUIRING the artist channel +
title. If nothing matches, the download produces no file and the job now fails
cleanly with "Nicht eindeutig gefunden — bitte Direktlink im Importer nutzen"
(previously it falsely reported success with no file).
Single, album and playlist paths all surface the not-found state.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>