- Add Category model with id, name, description, color fields
- Update Todo model with category_id foreign key relationship
- Create Category CRUD operations with full validation
- Add Category API endpoints with complete REST functionality
- Update Todo API and CRUD to support category filtering
- Create Alembic migration to add categories table
- Clean up code structure and remove unused references
- Update all import files and maintain proper relationships
Categories system enables better todo organization and filtering capabilities.
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