Allow users to configure multiple directory names per category (movie/series/anime) to support variations like "movies", "tv", "films". This enables proper categorization of files in directories that don't match the hardcoded singular forms, solving the issue where 635 files in "/mnt/Downloads/movies/" were incorrectly categorized as "other".
Configuration example:
categories:
movie: [movie, movies, films]
series: [series, tv, shows]
anime: [anime]
Changes include comprehensive validation, backward-compatible defaults, case-insensitive matching, and full test coverage (395 tests passing).
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
