feat(Phase 5): Complete Window/Scene Architecture

- Window singleton with properties (resolution, fullscreen, vsync, title)
- OOP Scene support with lifecycle methods (on_enter, on_exit, on_keypress, update)
- Window resize events trigger scene.on_resize callbacks
- Scene transitions (fade, slide_left/right/up/down) with smooth animations
- Full integration of Python Scene objects with C++ engine

All Phase 5 tasks (#34, #1, #61, #105) completed successfully.

src/PySceneObject.h

@@ -0,0 +1,63 @@
+#pragma once
+#include "Common.h"
+#include "Python.h"
+#include <string>
+#include <memory>
+
+// Forward declarations
+class PyScene;
+
+// Python object structure for Scene
+typedef struct {
+    PyObject_HEAD
+    std::string name;
+    std::shared_ptr<PyScene> scene;  // Reference to the C++ scene
+    bool initialized;
+} PySceneObject;
+
+// C++ interface for Python Scene class
+class PySceneClass
+{
+public:
+    // Type methods
+    static PyObject* __new__(PyTypeObject* type, PyObject* args, PyObject* kwds);
+    static int __init__(PySceneObject* self, PyObject* args, PyObject* kwds);
+    static void __dealloc(PyObject* self);
+    static PyObject* __repr__(PySceneObject* self);
+    
+    // Scene methods
+    static PyObject* activate(PySceneObject* self, PyObject* args);
+    static PyObject* get_ui(PySceneObject* self, PyObject* args);
+    static PyObject* register_keyboard(PySceneObject* self, PyObject* args);
+    
+    // Properties
+    static PyObject* get_name(PySceneObject* self, void* closure);
+    static PyObject* get_active(PySceneObject* self, void* closure);
+    
+    // Lifecycle callbacks (called from C++)
+    static void call_on_enter(PySceneObject* self);
+    static void call_on_exit(PySceneObject* self);
+    static void call_on_keypress(PySceneObject* self, std::string key, std::string action);
+    static void call_update(PySceneObject* self, float dt);
+    static void call_on_resize(PySceneObject* self, int width, int height);
+    
+    static PyGetSetDef getsetters[];
+    static PyMethodDef methods[];
+};
+
+namespace mcrfpydef {
+    static PyTypeObject PySceneType = {
+        .ob_base = {.ob_base = {.ob_refcnt = 1, .ob_type = NULL}, .ob_size = 0},
+        .tp_name = "mcrfpy.Scene",
+        .tp_basicsize = sizeof(PySceneObject),
+        .tp_itemsize = 0,
+        .tp_dealloc = (destructor)PySceneClass::__dealloc,
+        .tp_repr = (reprfunc)PySceneClass::__repr__,
+        .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  // Allow subclassing
+        .tp_doc = PyDoc_STR("Base class for object-oriented scenes"),
+        .tp_methods = nullptr,  // Set in McRFPy_API.cpp
+        .tp_getset = nullptr,   // Set in McRFPy_API.cpp
+        .tp_init = (initproc)PySceneClass::__init__,
+        .tp_new = PySceneClass::__new__,
+    };
+}