Light mode and tracking categories for prepayments

Users can now toggle between dark and light themes using a sun/moon icon located in the top-right corner of the interface.

The update enables users to add a tracking category to a prepayment schedule. Once assigned, the system automatically applies this tracking category to every journal entry the schedule generates.

Two-factor authentication is now required for all accounts. Users can configure this in advance by navigating to Settings → User settings → Enable MFA, or they will be prompted to set it up upon their next sign-in.