port EterLib/GrpLightManager.cpp verbatim, initialise CLightManager (unit B)

Replaces the platform_stub skeleton with the 40250 source and mirrors
m_LightManager.Initialize() from 40250 PythonApplication.cpp:1263.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

extension/src/platform/UserInterface/PythonApplication.cpp

@@ -136,6 +136,10 @@ bool CPythonApplication::Create(PyObject*, const char*, int, int, int)
 	// 40250 PythonApplication.cpp:1260.
 	CPythonTextTail::Instance().Initialize();
 
+	// 40250 PythonApplication.cpp:1262-1263.
+	// Light Manager
+	m_LightManager.Initialize();
+
 	if (IsNativeTerrainRenderEnabled())
 	{
 		const bool use_hardware_cursor = PythonBoot::HostHardwareCursorEnabled();