tests: assert players stay on the floor in the game-flow multiplayer test too

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ

scripts/mp_game_flow_client.gd

@@ -59,13 +59,19 @@ func _run() -> void:
 			await process_frame
 		quit(0); return
 
-	# role a: move and look for a remote node.
+	# role a: hold still briefly (confirm we don't fall through the floor),
+	# then move and look for a remote node.
 	var player = game.get_node("Player")
+	var min_y := 1000.0
+	for i in 30:
+		await process_frame
+		min_y = minf(min_y, player.global_position.y)
+	var on_floor: bool = min_y > -3.0
+
 	var start: Vector3 = player.global_position
 	var max_remotes := 0
 	for i in 120:
-		# Drive the player forward by faking held input.
-		player._input_direction = Vector2(0, 1)
+		player._input_direction = Vector2(0, 1)  # fake held forward
 		await process_frame
 		var n := 0
 		for c in game.get_children():
@@ -73,5 +79,5 @@ func _run() -> void:
 				n += 1
 		max_remotes = maxi(max_remotes, n)
 	var moved: bool = player.global_position.distance_to(start) > 1.0
-	print("RESULT a remotes=%d moved=%s" % [max_remotes, str(moved)])
-	quit(0 if (moved and max_remotes >= 1) else 1)
+	print("RESULT a remotes=%d moved=%s on_floor=%s" % [max_remotes, str(moved), str(on_floor)])
+	quit(0 if (moved and max_remotes >= 1 and on_floor) else 1)