Use Cap instead of hCAPTCHA (for the flagship instance)

Speaking as an end-user and as someone who cares about accessibility: I'm bad at visual puzzles. Sometimes, hCaptcha's puzzles are so visually distorted that I genuinely can't solve them. They're also inaccessible to those who might be using screen readers, visually impaired, or have motor issues. IMO, switching to any captcha solution that's based on PoW challenges lowers the barrier of entry to the app. I would suppose the problem lies in the cost of switching over, how that might affect existing users, etc. In any case, it should be painless for end-users to use or, better yet, none of their concern, since a captcha solution's main priority is keeping bots out.