Fix/cache validation

[HarshitR2004]

Description

Fixed cache invalidation bug in Library.add_album() where the _memotable cache was not cleared after adding albums, unlike the Library.add() method. This could lead to stale template cache data when adding albums with multiple items.

To Do

• Documentation. (If you've added a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• Changelog. (Add an entry to docs/changelog.rst to the bottom of one of the lists near the top of the document.)
• Tests. (Very much encouraged but not strictly required.)

[Copilot]

Pull Request Overview

Fixes a cache invalidation bug where Library.add_album() failed to clear the _memotable cache after adding albums, causing potential stale template data issues.

• Added cache clearing by setting _memotable to an empty dictionary after album insertion
• Updated changelog to document the bug fix

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/changelog.rst	Added changelog entry documenting the cache invalidation bug fix
beets/library/library.py	Added cache clearing statement to match behavior in Library.add() method

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[sourcery-ai]

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[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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[semohr]

Thanks for submitting this PR and your interest in contributing to beets.

I took a look at the change and had some questions about the motivation. The original _memotable functionality (from #4438) was added for a specific reason related to singleton tracks. I'm not sure the same issue applies to albums, and the PR description doesn't clarify the specific problem this solves.

To help us understand, could you please provide:

• A concrete example of the issue or bug this change fixes when working with albums.
• The specific motivation or use case that led you to make this change.

As your contributions appears to be AI-generated to me, I will take a bit more caution here! Often such PRs "fix" non-existent issues without a clear understanding of the codebase. These can unintentionally introduce bugs. If that's not the case here, I apologize for the assumption, and I look forward to your clarification so we can move forward.