Generate all Eloquent models for the Artworks module.

Requirements:
- Follow .copilot/artworks.md exactly
- Follow .copilot/instructions.md strictly
- Laravel 12, PHP 8.3+
- Use SoftDeletes only where allowed
- Define all relationships
- Add fillable arrays
- Add PHPDoc blocks for relations
- Do NOT add business logic
- Do NOT add observers

Models:
- Artwork
- ArtworkTranslation
- ArtworkStats
- ArtworkComment
- ArtworkDownload