Restructure C++ core into cpp module and package bindings.

Move the pricing engine sources out of src/ into cpp/, add the closed-form engine and pybind wiring, and align tests/build targets with the new project layout.

Made-with: Cursor

cpp/Option.hpp

@@ -0,0 +1,40 @@
+/**
+ * @file Option.hpp
+ * @brief Option instrument with exercise style (@ref Exercise).
+ */
+
+#ifndef QUANTENGINE_OPTION_HPP
+#define QUANTENGINE_OPTION_HPP
+#include "Instrument.hpp"
+#include "Exercise.hpp"
+
+/**
+ * @brief Extends @ref Instrument with exercise schedule / style metadata.
+ */
+class Option : public Instrument{
+public:
+    Option() = default;
+    virtual ~Option() = default;
+    Option(double maturity, std::unique_ptr<Exercise> exercise,
+        std::unique_ptr<Payoff> payoff, std::unique_ptr<PricingEngine> engine);
+    [[nodiscard]] Exercise& exercise() const {
+        return *exercise_;
+    }
+
+    [[nodiscard]] Exercise::Type exerciseType() const override { return exercise_->type(); }
+
+protected:
+    std::unique_ptr<Exercise> exercise_;
+};
+
+/** @brief Plain-vanilla option using the base @ref Option constructor. */
+class VanillaOption : public Option {
+public:
+    using Option::Option;
+};
+
+
+
+
+
+#endif //QUANTENGINE_OPTION_HPP