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/port/UserInterface/PythonSystem.h

@@ -110,6 +110,9 @@ class CPythonSystem : public CSingleton<CPythonSystem>
 		bool							IsAlwaysShowName();
 		bool							IsShowDamage();
 		bool							IsShowSalesText();
+		// PORT: AVA2 effect_level (0 all, 1 hide players/NPCs, 2 hide monsters/NPCs, 3 hide others, 4 hide all).
+		int								GetEffectLevel() { return m_iPortEffectLevel; }
+		void							SetEffectLevel(int iLevel) { m_iPortEffectLevel = iLevel < 0 || iLevel > 4 ? 0 : iLevel; }
 		bool							IsUseDefaultIME();
 		bool							IsNoSoundCard();
 		bool							IsAutoTiling();
@@ -159,4 +162,5 @@ class CPythonSystem : public CSingleton<CPythonSystem>
 		bool							m_isInterfaceConfig;
 		PyObject *						m_poInterfaceHandler;
 		TWindowStatus					m_WindowStatus[WINDOW_MAX_NUM];
+		int								m_iPortEffectLevel = 0;
 };