Add support for separate amounts within a single transaction

Currently, transactions created in the application can only be created with the total amount and a single assigned category. However, for a more detailed view, some users may prefer to add a list of individual amounts within a single transaction.

For example, if the transaction is assigned to the "Groceries" category, you should be able to add individual sub-amounts to individual sub-categories within a single transaction (e.g. $10 meat, $5 cheese, etc.). In the transaction list, you'll still see the parent category and the total amount ("Groceries"), but when you open the transaction details, you'll see the individual breakdown of subcategories and amounts.

Alternatively, you can already use the notes to enter the items and partial amounts.

Example from other apps: