feat: add reply_user to WalineChildComment

[AnzhiZhang]

reply_user is being used in CommentCard.vue but not included in types.

See also:

waline/packages/server/src/controller/comment.js

Lines 583 to 588 in 1003323

	c.reply_user = {
	nick: parent?.nick,
	link: parent?.link,
	avatar: parent?.avatar,
	};
	});