Track Short Position

[chengwah1]

Feature: Enable Short Position Tracking via Negative Quantity This PR introduces the ability to track short positions within the portfolio by allowing SELL_SHORT transaction quantities to be negative. https://github.com/afadil/wealthfolio/issues/339

Implementation Details I've updated the relevant logic to handle negative quantities, treating them as short sales. This allows users to accurately represent short positions in their holdings data.

Testing and Scope I've performed testing across key areas, and confirmed the following components are functioning correctly with negative quantities:

Performance Chart: Calculations correctly reflect P/L and value changes for short positions.

Data Import: Importing transactions with negative quantities works as expected.

Holdings View: Displays short positions and current values accurately. Holdings View: Limitation on displaying short position for Country Allocation and Sector Allocation (showing 0%)

Design Discussion: Negative Quantity Direction I noticed existing guarding code against negative quantities. This implementation uses the negative quantity as the primary signal for a short position. While functional, this might conflict with existing architectural assumptions or planned future features. I am completely open to discussing alternative approaches. Do let me know your thoughts!