Open redirect protection (https://www.pixiv.net/jump.php) is broken for novels

## Summary: I found that pixiv has a open redirect protection, any external link in illustration is converted to `https://www.pixiv.net/jump.php?<link provided by user>`. For example `https://i3mx4usociis8twimpcu2ty0erkh86.burpcollaborator.net/abc` in `https://www.pixiv.net/member_illust.php?mode=medium&illust_id=74148892` is converted to `https://www.pixiv.net/jump.php?https%3A%2F%2Fi3mx4usociis8twimpcu2ty0erkh86.burpcollaborator.net%2Fabc`. See the attachment "illust.png". However, that is not true for novels. Links in novel is shown to be converted to `jump.php` link in preview (see attachment "preview.png") but they actually aren't. See `https://www.pixiv.net/novel/show.php?id=109971051` and "novel.png" for an example. Since the "jump.php" protection mechanism is working for illusts and the preview of novels, I think lacking this protection for novels is not an intended behavior. ## Steps To Reproduce: 1. Add a novel 2. Choose "Add URL" and edit the content to something like `[[jumpuri:https://pixiv.net/ > https://i3mx4usociis8twimpcu2ty0erkh86.burpcollaborator.net/abc]]` 3. Save 4. You will see a link in the novel which reads `https://pixiv.net/` but actually it is `https://i3mx4usociis8twimpcu2ty0erkh86.burpcollaborator.net/abc`. See `https://www.pixiv.net/novel/show.php?id=10997105` for your reference. ## Impact Faking users to the wrong site