[FEATURE] Currency Script | Create a currency management module

[sue-lim]

The list of supported currencies is not maintained or easily searchable.

Describe the solution you'd like
Create currencies.py:

Store supported currencies
Provide a function to search/filter currencies

Describe alternatives you've considered
Hardcoding currencies in main.py, which is error-prone and hard to update.

Additional context
This will support future features like autocompletion or validation.

[sue-lim]

@DhanushNehru - please kindly assign this issue to me.
Many thanks