add Anubis with a conservative config

We haven't had a lot of problems from scrapers over the years because we have put a bunch of time into performance work, especially by using full-page caching for logged-out visitors to avoid even touching the app servers. That means we have the breathing room to take a very gradual, conservative approach to increasing mitigations like Anubis, which we should use to only challenge the riskiest traffic. An unusually high percentage of our users (unknown, but probably single-digit) cannot solve javascript proof-of-work challenges because they're using strict privacy/security controls, homebrewed browsers, or other unusual setups.

Saturday before last (2025-10-25) Lobsters was slow/mostly down because were were getting aggressively scraped by a bot that used many thousands of IPs to avoid rate-limiting.

In the immediate mitigation, I was able to block their IPs with iptables and a list of bad-actor IPs for ASINs owned by that network because cadey shared the list that's already in Anubis for them.

I also fixed the endpoint they overwhelmed in 5e29c8d60. It normally took ~8ms to look up a redirect, but the fact that it did 2-3 queries instead of serving a locally cached page allowed them to dogpile the database.

This probably isn't the only endpoint susceptible to abuse, nor the last aggressive scraper we'll see. So I'd like to add Anubis, conservatively configured to only challenge ASINs from its bad actor lists, which are here and here.