Currency on Account

[iamwales]

Is your feature request related to a problem? Please describe.
The current account model lacks currency support, making it difficult to handle multi-currency accounts. This could be problematic for future expansion in regions with different currencies.

Describe the solution you'd like
Introduce a Currency model that allows accounts to be linked to different currencies. This will enable the application to support multi-currency accounts and transactions.

Describe alternatives you've considered
Adding a simple currency field to the account model without a full currency entity.

Additional context
This feature would future-proof the application for international usage. It could also open the door to additional features like currency conversion, exchange rate tracking, and multi-currency balances.

[AmrElsayyad]

@iamwales You can add this contribution if you want. This is a project for learning and it's not meant for real production. We're open for contributions.