Cifra-Accounting/flutter-frontend

AI Summary: This issue proposes adding a user interface for creating categories, a feature currently absent from the application. A suggested approach is to implement a modal sheet for category creation within the existing transaction creation flow, though further design details are still open.

AI Summary: This issue addresses the problem of implementing category deletion, which currently leads to the deletion of all associated transactions because transactions are required to have a category. Two solutions are proposed: either refactor the entire transaction system to allow transactions without categories, or introduce a default 'no category' category to reassign transactions to upon deletion.