Multi genres / only "genres" field wip

[snejus]

No description provided.

Pull Request Overview

This pull request migrates genre handling by replacing the singular "genre" field with the plural "genres" field across the codebase. Key changes include:

• Introducing a new property "genre" that wraps the underlying "genres" field in LibModel.
• Updating getter functions and field definitions in Item, Album, and related modules to use "genres".
• Adjusting tests and autotag hooks to reflect the new "genres" field format.

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
beets/dbcore/db.py	Changed field update methods to use setattr instead of dict-style assignment and updated setattr logic.
beets/library.py	Added a property for genre and updated _getters as well as field definitions for Item and Album.
beets/dbcore/types.py	Modified DelimitedString type by introducing a normalize method before serializing to SQL.
beets/autotag/mb.py	Replaced usage of "genre" with "genres" in metadata construction.
beets/autotag/hooks.py	Adjusted TrackInfo initialization to set genres from genre, ensuring a list is stored.
beets/autotag/init.py	Updated field assignment from dict-style to attribute assignment using setattr.
test/test_library.py	Updated tests to handle changed field names from "genre" to "genres".
test/test_sort.py	Modified sorting tests to validate on label changes instead of genre.
test/test_ui.py	Adjusted update tests to target the "genres" field.

Files not reviewed (1)

• docs/changelog.rst: Language not supported