- Changed UI input from 'Underlying units' to 'Initial portfolio value ($)'
- Underlying units are now calculated as initial_value / entry_spot
- Updated default value to workspace gold_value instead of gold_ounces * entry_spot
- Result summary now shows both 'Initial value' and 'Underlying units'
- This allows users to specify how much they invest on day 1, and the system
automatically calculates the maximum purchasable shares/contracts