feat: Implement Power option pricing model

[joaquinbejar]

Description

Implement pricing support for Power options. Power options have payoffs that are a power function of the underlying asset price.

Current State

• Power options return PricingError::UnsupportedOptionType
• No pricing model for non-linear payoffs

Target State

• Fully functional Power option pricing
• Support for various power exponents
• Accurate pricing of non-linear payoffs

Tasks

• Implement standard power option pricing
• Implement capped power options
• Support both call and put variants
• Handle various power exponents (n = 2, 3, etc.)
• Implement Greeks calculations
• Add comprehensive tests
• Add documentation with examples

Technical Notes

Standard Power Call: Payoff = max(S^n - K, 0)
Powered Payoff: Payoff = [max(S - K, 0)]^n

For squared power call (n=2), S_T^2 is log-normal with adjusted parameters.

General formula: E[S^n] = S^n * e^(n*(r-q)T + n(n-1)sigma^2T/2)

Considerations: Higher powers increase leverage and risk, Greeks can be very large.

Estimated Effort

Medium (6-8 hours)