Proposal: new hook to detect LFS attribute inconsistencies

There are two common errors when working with LFS:

• Keeping files as general objects after setting LFS attributes (LFS produces a warnings like "Encountered 1 file(s) that should have been pointers, but weren't")
• Keeping LFS pointers after removing the attributes.

Proposed implementation of a check-lfs-attributes hook: https://github.com/klimkin/pre-commit-hooks/tree/feature/check-lfs-attributes

Start by reviewing the proposed check-lfs-attributes implementation at the linked branch, then compare it with the repository's existing hook patterns. Verify both reported cases: tracked files that should be LFS pointers and LFS pointers whose attributes were removed; done means the hook detects each inconsistency reliably.