Category Groups for Reports

Add the ability to organize categories into higher-level groups, such as Housing, Utilities, Transportation, Health & Fitness, etc., and display those groupings in reports.

Currently, reports show categories in a flat list. This feature would allow users to create or assign categories to groups so the income and expense report can be viewed in a more organized, management-report style format, while still keeping the default experience simple for users who do not need grouping.