Created the first working version of the transaction system. Income and expenses are now accepted, and actual data rather than hardcoded amounts are used to update balance, income, and spending in real time. Also created transaction saving to localStorage.

Discovered a bug early on where an invalid input broke all calculations, so I added a better validation in the form to (hopefully) prevent these types of errors in the future.

For now, I’ll keep working on the UX part and create more features and then move on to UI.