feat: add Dust 2 level builder and implement pause menu UI with settings and loadout management

debug/dust2_level_builder.gd

@@ -208,6 +208,11 @@ func _build_dust2_layout() -> void:
 	add_child(combat_area)
 
 func _build_dust2_dummies() -> void:
+	# Do not spawn dummies in real multiplayer matches
+	var nm = get_node_or_null("/root/NetworkManager")
+	if nm and nm.multiplayer.multiplayer_peer is ENetMultiplayerPeer:
+		return
+		
 	var spawn_dummy = func(pos: Vector3, rot_y: float):
 		var dummy = load("res://entities/killable_dummy.gd").new()
 		dummy.position = pos

ui/pause_menu.gd

@@ -684,6 +684,7 @@ func _show_return_dialog() -> void:
 
 func _return_to_main_menu() -> void:
 	_resume() # Reset pause state and cursor mode
+	NetworkManager.disconnect_game()
 	get_tree().change_scene_to_file("res://ui/main_menu/main_menu.tscn")
 
 func _show_main_menu() -> void: