port: FlyingData/Instance/ObjectManager/FlyTrace + effect/fly modules (batch 2 P1)

Verbatim copies of the 40250 flying-object units and the effect/fly
Python modules replace the pending CFlyingManager stand-in and the two
module stubs; initeffect/initfly run after initnet as in 40250 and the
flying manager gets the background as its map manager.
CMapManager::GetTerrainHeight is added over the native height tiles.
login_flow checks playersettingmodule registered the indexed fly data.

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

extension/src/platform/ScriptLib/PythonBoot.cpp

@@ -319,6 +319,7 @@ bool Start(const char* stdlib_path, std::string* error)
 	g_effect_manager = std::make_unique<CEffectManager>();
 	g_game_application = std::make_unique<GameApplicationAdapter>();
 	g_game_singletons = std::make_unique<GameSingletons>();
+	g_flying_manager->SetMapManagerPtr(&g_game_singletons->pyBackground); // 40250 CPythonApplication ctor (PythonApplication.cpp:82)
 	return true;
 }
 
@@ -344,6 +345,8 @@ bool run_main_script_body(const char* lpCmdLine, std::string* error)
 	initPlayer();
 	initChat();
 	initnet();
+	initeffect();
+	initfly();
 	init_2v0_gameplay_stubs();
 
 	ClearLogBoxMessage();