Anti-Spam on email registrations

[frenzybiscuit]

So I know we can use other providers like GitHub and stuff, but for regular email registrations it would be cool if there was some kind of antispam in place.

No rush, it's just a nice-to-have feature, not really a deal breaker or even a priority feature.

Something like this:

[rubentalstra]

@frenzybiscuit have you seen my PR: 🚀 feat: Add Cloudflare Turnstile support