feat: implement main scene initialization and add screen shake and stop-n-go game managers

scenes/main.gd

@@ -171,6 +171,11 @@ func _hide_ground_tiles():
 func _setup_effect_elevation():
 	var em = get_node_or_null("EnhancedGridMap")
 	if em and em.mesh_library:
+		# USER REQUEST: Do not apply visual Y-elevation for walls in Stop n Go mode
+		if LobbyManager.game_mode == "Stop n Go":
+			print("[Main] Stop n Go mode detected: Skipping effect elevation for walls.")
+			return
+
 		var ml = em.mesh_library.duplicate()
 		
 		# Height 0.8: Above 3D arena, but below pickups (Y=1.0)
@@ -183,6 +188,7 @@ func _setup_effect_elevation():
 		em.mesh_library = ml
 		print("[Main] MeshLibrary elevation applied: Wall(4) and Freeze(5) at Y=0.8")
 
+
 @rpc("any_peer", "call_local", "reliable")
 func sync_portal_configs(configs: Array):
 	if portal_mode_manager: