Register observable 2V0 gameplay stubs through RunApp

extension/src/python_host_node.h

@@ -6,8 +6,8 @@
 //       var err := Metin2PythonHost.run_main_script("")
 //
 // Both calls answer with "" on success and with the reason otherwise, so GDScript never has to guess
-// from a bool. Until 批次 2V0 registers the C++ modules, run_main_script() is expected to come back with
-// system.py's first import error; that is what step 4 verifies on each target platform.
+// from a bool. 2V0-e reaches prototype.RunApp(); until 2V0-f implements the application adapter,
+// app.Create reports CREATE_DEVICE and the original script displays its error popup.
 //
 // This is the only unit that knows both godot-cpp and the port tree: the sequence itself lives in
 // platform/ScriptLib/PythonBoot.h, which stays godot-free.