Add AVA2-style display options (effect level, trees, clouds)

Client-only port of ENABLE_GRAPHIC_ON_OFF / HIDE_OBJECTS: five effect
levels toggle attached actor effects via Active/Deactive, tree and cloud
parts use background.SetVisiblePart, plus shortcuts for the original
name and damage options. mt_display window, mt_display.cfg, port.display
test, docs/AVA2-DISPLAY.md.

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

src/platform/ScriptLib/PythonBoot.cpp

@@ -1001,6 +1001,7 @@ namespace PythonBoot
 #include "WikiEntryScript.inc"
 #include "SwitchbotScript.inc"
 #include "PickupScript.inc"
+#include "DisplayScript.inc"
 
 static void install_script_module(const char* c_szModule, const char* c_szScript)
 {
@@ -1076,6 +1077,7 @@ bool RunMainScript(const char* lpCmdLine, std::string* error)
 		install_script_module("mt_wiki_entries", c_szWikiEntryScript);
 		install_script_module("mt_switchbot", c_szSwitchbotScript);
 		install_script_module("mt_pickup", c_szPickupScript);
+		install_script_module("mt_display", c_szDisplayScript);
 		if (g_touch_input)
 			install_script_module("mt_mobile_hud", c_szMobileHUDScript);
 	}