Implement Portfolio Performance Calculation

[grantfox-oss]

Description:
Calculate comprehensive portfolio performance metrics including total return, ROI, allocation percentages, and risk-adjusted metrics (Sharpe ratio, maximum drawdown).

Acceptance Criteria:

• Total portfolio value calculation
• Return on Investment (ROI) percentage
• Allocation percentages by asset
• Allocation by category (crypto, stocks, commodities)
• Time-weighted return (TWR) calculation
• Sharpe ratio (with configurable risk-free rate)
• Maximum drawdown identification
• Performance vs benchmark comparison

Definition of Done:

• Performance metrics calculated correctly
• Results verified against manual calculation
• Performance updates on portfolio changes
• Unit tests > 90% coverage

Test Requirements:

• Unit tests for each metric
• Known result test cases
• Edge case tests (empty portfolio, single asset)

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[primexk5]

GM MAINTAINER, I WISH TO WORKING ON THIS AND CREATE A PULL REQUEST IMMEDIATELY! THANK YOU!

[Thirumurugan7]

I have experience with this. I can complete this issue ASAP

Checkout my portfolio: 0xthiru.xyz

[grantfox-oss]

🦊 GrantFox — @primexk5 has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #32)
2. Your PR will be reviewed by the SourceXXL maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@primexk5's PR #41 was approved and merged by @memplethee-lab.

🏆 @primexk5: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (293 total points). Track your full progress on GrantFox.

👏 Great work, @primexk5! Keep contributing to SourceXXL.