Create option pricing engine structure, test architecture.

src/MarketData.cpp

@@ -0,0 +1,9 @@
+//
+// Created by David Doebel  on 06.03.2026.
+//
+
+#include "MarketData.hpp"
+
+double MarketData::spot() const { return spot_; }
+YieldCurve& MarketData::yield_curve() { return *yield_curve_; }
+VolatilitySurface& MarketData::volatility_surface() { return *volatility_surface_; }