feat: Individual positions per holding

[philicious]

Problem or use case

I'd like to see my current positions per holding (stock) to better track performance of my past buys/sells and plan ahead

Currently I am reconstructing that based on transaction history by FIFO principle

Proposed solution

No response

Alternatives considered

No response

Relevant command or workflow

sc holdings

User impact

Important for a specific workflow

Checklist

• I have searched existing issues.
• This is a CLI feature request, not an account/support request.
• I understand this repository is source-available and does not accept external PRs.