fix(Characters): 修复Bear冲刺时未检查boss有效性的问题

修复Bear.gd中sprint函数未检查currentFocusedBoss是否有效的问题，避免潜在崩溃
调整TickTool.gd中until方法的frame调用方式
修改Wave.gd测试环境下的初始波次配置

scripts/Contents/Characters/Bear.gd

@@ -122,8 +122,8 @@ func attack(type):
 		return false
 	return true
 func sprint():
-	var dir = sign((currentFocusedBoss.position - position).x)
-	velocity = Vector2(dir, 0)
+	if is_instance_valid(currentFocusedBoss):
+		velocity = Vector2(sign((currentFocusedBoss.position - position).x), 0)
 func sprintAi():
 	velocity.x *= 1.2
 	return abs(velocity.x) >= 1000000