feat: implement new 'Stop N Go' arena scene and manager.

scenes/main.gd

@@ -92,8 +92,6 @@ func _setup_multiplayer_spawners():
 
 func _apply_arena_background():
 	var arena_bg = get_node_or_null("ArenaBG")
-	if not arena_bg:
-		return
 		
 	var selected_area = LobbyManager.get_selected_area()
 	var texture_path = ""
@@ -103,17 +101,29 @@ func _apply_arena_background():
 			texture_path = "res://assets/graphics/level_bg/level_bg_colloseum.jpg"
 		"Stop N Go Arena":
 			texture_path = "res://assets/graphics/level_bg/placeholder_stop_n_go.jpg"
+			_instantiate_3d_arena("res://scenes/arena/stop_n_go.scn")
 		"Tekton Doors Arena":
 			texture_path = "res://assets/graphics/level_bg/placeholder_tekton_doors.jpg"
 		"Classic", _:
 			texture_path = "res://assets/graphics/level_bg/placeholder_classic.jpg"
 			
-	if ResourceLoader.exists(texture_path):
-		var tex = load(texture_path)
-		if tex:
-			arena_bg.texture = tex
-	else:
-		print("Arena bg texture not found: ", texture_path)
+	if arena_bg and texture_path != "":
+		if ResourceLoader.exists(texture_path):
+			var tex = load(texture_path)
+			if tex:
+				arena_bg.texture = tex
+		else:
+			print("Arena bg texture not found: ", texture_path)
+
+func _instantiate_3d_arena(scene_path: String):
+	if ResourceLoader.exists(scene_path):
+		var arena_scene = load(scene_path)
+		if arena_scene:
+			var arena_instance = arena_scene.instantiate()
+			arena_instance.name = "ArenaEnvironment3D"
+			add_child(arena_instance)
+			move_child(arena_instance, 0)
+			print("Instantiated 3D Arena: ", scene_path)
 
 @rpc("any_peer", "call_local", "reliable")
 func sync_portal_configs(configs: Array):
@@ -665,7 +675,8 @@ func _start_game():
 		# PRE-GAME COUNTDOWN (3s)
 		# Spawn static obstacles before countdown starts (Stop n Go only)
 		if obstacle_manager and LobbyManager.game_mode == "Stop n Go":
-			obstacle_manager.spawn_random_obstacles(15)
+			# obstacle_manager.spawn_random_obstacles(15) # Disabled: Using fixed obstacles now
+			pass
 			
 		# Spawn mission and power-up tiles BEFORE countdown but AFTER walls (Stop n Go only)
 		if LobbyManager.game_mode == "Stop n Go" and stop_n_go_manager: